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NCERT Solutions for Class 10 Maths Chapter 3: Pair of Linear Equations in Two Variables - Exercise 3.7

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NCERT Solutions for Class 10 Maths Chapter 3 Pair of Linear Equations in Two Variables

NCERT Solutions for Class 10 Maths Chapter 3 Exercise 3.7 are available on Vedantu in PDF format and can be downloaded for free. Exercise 3.7 Class 10 Maths deals with linear equations in two variables. To solve a linear equation in two variables we need at least two equations. To understand the concepts of the chapter in detail, refer to the Exercise 3.7 Class 10 Maths NCERT Solutions PDF. These solutions are prepared by our highly experienced faculty members. The PDF contains a simple and logical explanation of all the concepts covered in the chapter. You can also Download Maths NCERT Solutions Class 10 to help you to revise the complete Syllabus and score more marks in your examinations. If you are looking for study materials for science then you can download NCERT Solutions Class 10 Science for free only from Vedantu.


Class:

NCERT Solutions for Class 10

Subject:

Class 10 Maths

Chapter Name:

Chapter 3 - Pair of Linear Equations in Two Variables

Exercise:

Exercise - 3.7

Content-Type:

Text, Videos, Images and PDF Format

Academic Year:

2024-25

Medium:

English and Hindi

Available Materials:

  • Chapter Wise

  • Exercise Wise

Other Materials

  • Important Questions

  • Revision Notes



All Topics and Subtopics of NCERT Class 10 Maths Chapter 3 - Pair of Linear Equations in Two Variables

The sub-topics of chapter 3 Maths are given below.


S.No

Topic Name

3.1

Introduction

3.2

Pair of Linear Equations in Two Variables

3.3

Graphical Method of Solution of a Pair of Linear Equations

3.4

Algebraic Methods of Solving a Pair of Linear Equations

3.4.1

Substitution Method

3.4.2

Elimination Method

3.4.3

Cross - Multiplication Method

3.5

Equations Reducible to a Pair of Linear Equations in Two Variables

3.6

Summary



Important Points

  • A pair of linear equations in two variables is described as the two linear equations that deal with the same two variables. It can be represented as:

a1x+b1y+c1=0

a2x+b2y+c2=0

Where a1, a2, b1, b2, c1 and c2 are the real numbers.

  • The pair of linear equations can be represented in a graph using two lines. Using these two lines of nature, we can predict the number of solutions of the pair of linear equations in two variables. 

How Do Lines Meet?

Number of Solutions

Lines intersect at a point

Unique solution

Lines coincide

Infinitely many solutions

Lines are parallel

No solution

  • If two equations a1x+b1y+c1=0 and a2x+b2y+c2=0 are given, then the nature of pair of linear equations can be find as:

Condition

Nature of Pair of Linear Equation

\[\frac{a_{1}}{a_{2}} \neq \frac{b_{1}}{b_{1}}\]

Pair of linear equations is consistent.

\[\frac{a_{1}}{a_{2}} = \frac{b_{1}}{b_{2}} \neq \frac{c_{1}}{c_{2}}\]

Pair of linear equations is inconsistent.

\[\frac{a_{1}}{a_{2}} = \frac{b_{1}}{b_{2}} = \frac{c_{1}}{c_{2}}\]

Pair of linear equations is dependent and consistent.

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Access NCERT Solutions Class 10 Mathematics Chapter 3 – Pair of Linear Equations in Two Variables

Exercise 3.7

1. The ages of two friends Ani and Biju differ by 3 years. Ani’s father Dharam is twice as old as Ani and Biju is twice as old as his sister Cathy. The ages of Cathy and Dharam differ by 30 years. Find the ages of Ani and Biju.

Ans:

The age gap between Biju and Ani is a whopping 3. Biju is either 3 older than Ani, or Biju is 3 older than Ani.

However, it is self-evident that Ani's father's age will be 30 more than Cathy's age in both situations.

Let us assume that the age of Ani and Biju be x and y years.

Therefore, age of Ani’s father i.e. Dharam will be 2 × x=2x years 

And age of Biju’s sister Cathy = \[\dfrac{\text{y}}{\text{2}}\]

 years

Using the data provided in the question,

Case (I) When Ani is older than Biju by 3 years,

\[\text{x-y}\ \text{=}\ \text{3}\]   (i)  

\[\text{4x-y}\ \text{=}\ 60\]    (ii)

On subtracting (i) from (ii), we get

\[\text{3x}\ \text{=}\ \text{60-3}\ \text{=}\ \text{57}\]

\[\text{x}\ \text{=}\ \dfrac{57}{3}\ =\ 19\]

Therefore, age of Ani = 19 years 

And age of Biju =19-3 = 16 years

Case (II) if Biju is older than Ani, \[\text{y-x}\,\text{=}\ \text{3}\]

\[\text{2x-}\dfrac{\text{y}}{\text{2}}\ \text{=}\ \text{30}\]    (i)    

\[\text{4x-y}\ \text{=}\ \text{60}\]         (ii)

Adding (i) and (ii), we get 

\[\text{3x}\ \text{=}\ \text{63}\]

\[\text{x}\ \text{=}\ \text{21}\]

Hence, age of Ani =

\[\text{21}\]

years 

And also the age of Biju will be

\[text{21+3}\ \text{=}\ \text{24}\]

years
 

2. One says, “Give me a hundred, friend! I shall then become twice as rich as you”. The other replies, “If you give me ten, I shall be six times as rich as you”. Tell me what is the amount of their (respective) capital? (From the Bijaganita of Bhaskara II)

(Hint: \[\text{x+100}\ \text{=}\ \text{2(y-100),}\ \text{y+10}\ \text{=}\ \text{6(x-10)}\])

Ans:

Let those friends have Rs. x and y with them. 

Using the data provided in the question,

\[\text{x+100}\ \text{=}\ \text{2(y-100)}\]

\[\text{x+100}\ \text{=}\ \text{2y-200}\]

\[\text{x-2y}\ \text{=}\ -3\text{00}\]

(i) 

And

\[\text{6(x-10)}\ \text{=}\ \text{y+10}\]

\[\text{6x-60}\ \text{=}\ \text{y+10}\]

\[\text{6x-y}\ \text{=}\ 7\text{0}\]

(ii)

Multiplying equation (ii) by

\[2\]

, we get 

\[\text{12x-2y}\ \text{=}\ \text{140}\]

On subtracting equation (i) from equation (iii), we get 

\[\text{11x}\ \text{=}\ \text{140+300}\ \text{=}\ \text{440}\]

\[\text{x}\ \text{=}\ \text{40}\]

Using this in equation (i), we get 

\[\text{40-2y}\ \text{=}\ \text{-300}\]

\[\text{40+300}\ \text{=}\ \text{2y}\]

\[\text{2y}\ \text{=}\ \text{340}\]

\[\text{y}\ \text{=}\ 170\]

Therefore, those friends had Rs. 40 and Rs. 170

with them respectively.

3. A train covered a certain distance at a uniform speed. If the train would have been \[\text{10}\ \text{km/hr}\] faster, it would have taken 2 hours less than the scheduled time. And if the train were slower by \[\text{10}\ \text{km/hr}\]. it would have taken 3 hours more than the scheduled time. Find the distance covered by the train.

Ans:

Let the speed of the train be \[\text{x}\ \text{km/hr}\] and the time taken by train to travel the given distance be t hours and the distance to travel was \[\text{d}\ \text{km}\]. We know that,

\[\text{speed}\ \text{=}\ \dfrac{\text{distance}\ \text{travelled}}{\text{time}\ \text{taken}\ \text{to}\ \text{travel}\ \text{that}\ \text{distance}}\]

\[\text{x}\ \text{=}\ \dfrac{\text{d}}{\text{t}}\]

Or,

\[\text{d}\ \text{=}\ \text{xt}\]

(i)

Using the data provided in the question,

\[\text{(x+10)}\ \text{=}\ \dfrac{\text{d}}{\text{(t-2)}}\]

\[\text{(x+10)(t-2)}\ \text{=}\ \text{d}\]

\[\text{xt+10t+2x+20 = d}\]

By using equation (i), we get

\[\text{-2x+10t = 20}\]

(ii)

\[\text{(x-10)}\ \text{=}\ \dfrac{\text{d}}{\text{(t+3)}}\]

\[\text{(x-10)(t+3)}\ \text{=}\ \text{d}\]

\[\text{xt-10t+3x-30 = d}\]

By using equation (i), we get 

\[\text{3x-10t}\ \text{=}\ \text{30}\]

(iii)

On adding equation (ii) and (iii), we get 

\[\text{x = 50}\]

Using equation (ii), we get 

\[\text{(-2)(50)+10t = 20}\]

\[\text{-100+10t = 20}\]

\[\text{10t = 120}\]

\[\text{t = 12}\]

hours

From equation (i), we get 

Distance to travel =

\[\text{d}\ \text{=}\ \text{xt}\]

=

\[\text{50}\times \text{12}\]

=

\[\text{600}\ \text{km}\]

Hence, the distance covered by the train is

\[\text{600}\ \text{km}\].

4. The students of a class are made to stand in rows. If 3 students are extra in a row, there would be 1 row less. If 3students are less in a row, there would be 2 rows more. Find the number of students in the class.

Ans:

Let the number of rows be x and number of students in a row be y 

Total students of the class = Number of rows × Number of students in a row = \[\text{xy}\]

Using the data provided in the question,

Condition 1 

Total number of students =

\[\text{(x-1)(y+3)}\]

\[\text{xy = xy-y+3x-3}\]

\[\text{3x-y = 3}\]

(i)

Condition 2 

Total number of students =

\[\text{(x+2)(y-3)}\]

\[\text{xy = xy+2y-3x-6}\]

\[\text{3x-2y = -6}\]

(ii)

On subtracting equation (ii) from (i), 

\[\text{(3x-y)-(3x-2y) = 3-(-6)}\]

\[\text{-y+2y}\ \text{=}\ \text{3+6}\]

\[\text{y = 9}\]

By using equation (i), we get 

\[\text{3x-9}\ \text{=}\ \text{3}\]

\[\text{3x}\ \text{=}\ 9+3\ =\ 12\ \Rightarrow \ \text{x}\ \text{=}\ \text{4}\]

Number of rows =

\[4\]

Number of students in a row =

\[9\] 

Number of total students in a class =

\[4\times 9\ =\ 36\]
 

5. In a triangle ABC, \[\angle \text{C}\ =\ 3\angle \text{B}\ =\ 2(\angle \text{A}+\angle \text{B})\]. Find the three angles.

Ans:

\[\angle \text{C}\ =\ 3\angle \text{B}\ =\ 2(\angle \text{A}+\angle \text{B})\] 

\[3\angle \text{B}\ =\ 2(\angle \text{A}+\angle \text{B})\]

\[3\angle \text{B}\ =\ 2\angle \text{A}+2\angle \text{B}\] 

\[\angle \text{B}\ =\ 2\angle \text{A}\]

\[2\angle \text{A}-\angle \text{B}\ =\ 0\]

(i)

As we already know, the sum of the measures of all angles of a triangle is

\[{{180}^{\bullet }}\].

Therefore,

\[\angle \text{A+}\angle \text{B+}\angle \text{C}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

\[\angle \text{A+}\angle \text{B+3}\angle \text{B}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

\[\angle \text{A+4}\angle \text{B}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

(ii) 

Multiplying equation (i) by\[4\], we get

\[8\angle \text{A-4}\angle \text{B}\ \text{=}\ 0\]

(iii)

On adding equation (ii) and (iii), we get

\[9\angle \text{A}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

\[\angle \text{A}\ \text{=}\ 2{{\text{0}}^{\bullet }}\]

From equation (ii), we get 

\[2{{\text{0}}^{\bullet }}+4\angle \text{B}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

\[4\angle \text{B}\ \text{=}\ \text{16}{{\text{0}}^{\bullet }}\]

\[\angle \text{B}\ \text{=}\ 4{{\text{0}}^{\bullet }}\]

\[\angle \text{C}\ \text{=}\ 3\angle \text{B}\ \text{=}\ \text{3}\times \text{4}{{\text{0}}^{\bullet }}\ =\ {{120}^{\bullet }}\]

Therefore,

\[\angle \text{A}\ \text{=}\ 2{{\text{0}}^{\bullet }}\],

\[\angle \text{B}\ \text{=}\ 4{{\text{0}}^{\bullet }}\],

\[\angle \text{C}\ \text{=}\ \text{12}{{\text{0}}^{\bullet }}\]
 

6. Draw the graphs of the equation \[\text{5x-y}\ \text{=}\ \text{5}\] and\[\text{3x-y}\ \text{=}\ 3\]. Determine the coordinates of the vertices of the triangle formed by these lines and the \[\text{y}\]-axis.

Ans:

\[\text{5x-y}\ \text{=}\ \text{5}\] Or, \[\text{y}\ \text{=}\ \text{5x-5}\]

The solution table will be as follows: 

x

0

1

2

y

-5

0

5

\[\text{3x-y}\ \text{=}\ 3\].

Or,

\[\text{y}\ \text{=}\ 3\text{x-3}\]

The solution table will be as follows: 

x

0

1

2

y

-3

0

3


Graphical representation of these lines is given by


Graphical representation of Given Lines


Graphical representation of Given Lines


It can be observed that the required triangle is SABC formed by these lines and \[\text{y}\] -axis 

The coordinates of vertices are \[\text{A(1,0),}\ \text{B(0,-3),}\ \text{C(0,-5)}\]

7. Solve the following pair of linear equation.

(i) \[\text{px+qy}\ \text{=}\ \text{p-q}\] and \[\text{qx-py}\ \text{=}\ \text{p+q}\]

Ans:

\[\text{px+qy}\ \text{=}\ \text{p-q}\]

(1)

\[\text{qx-py}\ \text{=}\ \text{p+q}\]

(2)

Multiplying equation (1) by p and equation (2) by q , we get

\[{{\text{p}}^{\text{2}}}\text{x+pqy}\ \text{=}\ {{\text{p}}^{\text{2}}}\text{-pq}\]

(3)

\[{{\text{q}}^{\text{2}}}\text{x-pqy}\ \text{=}\ {{\text{q}}^{\text{2}}}\text{+pq}\]

(4)

On adding equation (3) and (4), we get

\[{{\text{p}}^{\text{2}}}\text{x+}{{\text{q}}^{\text{2}}}\text{x}\ \text{=}\ {{\text{p}}^{\text{2}}}\text{+}{{\text{q}}^{\text{2}}}\]

\[\text{(}{{\text{p}}^{\text{2}}}\text{+}{{\text{q}}^{\text{2}}}\text{)x}\ \text{=}\ {{\text{p}}^{\text{2}}}\text{+}{{\text{q}}^{\text{2}}}\]

\[\text{x}\ =\ 1\]

From equation (1), we get

\[\text{p(1)+qy}\ \text{=}\ \text{p-q}\]

\[\text{qy}\ \text{=}\ \text{-q}\]

\[\text{y}\ \text{=}\ \text{-1}\]
 

(ii)

\[\text{ax+by}\ \text{=}\ \text{c}\] and \[\text{bx+ay}\ \text{=}\ 1+\text{c}\]

Ans:

\[\text{ax+by}\ \text{=}\ \text{c}\]

(1)

\[\text{bx+ay}\ \text{=}\ 1+\text{c}\]

(2)

Multiplying equation (1) by a and equation (2) by b, we get

\[{{\text{a}}^{\text{2}}}\text{x+aby}\ \text{=}\ \text{ac}\]

(3)

\[{{\text{b}}^{\text{2}}}\text{x+aby}\ \text{=}\ \text{b+bc}\]

(4)

On subtracting equation (4) from equation (3),

\[\text{(}{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}\text{)x}\ \text{=}\ \text{ac-bc-b}\]

\[\text{x}\ \text{=}\ \dfrac{\text{c(a-b)-b}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\]

From equation (1), we get

\[\text{ax+by}\ \text{=}\ \text{c}\]

\[\text{a }\!\!\{\!\!\text{ }\dfrac{\text{c(a-b)-b}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\text{ }\!\!\}\!\!\text{ +by}\ \text{=}\ \text{c}\]

\[\dfrac{\text{ac(a-b)-ab}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\text{+by}\ \text{=}\ \text{c}\]

\[\text{by}\ \text{=}\,\text{c-}\dfrac{\text{ac(a-b)-ab}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\]

\[\text{by}\ \text{=}\,\dfrac{{{\text{a}}^{\text{2}}}\text{c-}{{\text{b}}^{\text{2}}}\text{c-}{{\text{a}}^{\text{2}}}\text{c+abc+ab}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\]

\[\text{by}\ \text{=}\,\dfrac{\text{-}{{\text{b}}^{\text{2}}}\text{c+abc+ab}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\]

\[\text{by}\ \text{=}\,\dfrac{\text{bc(a-b)+ab}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\]

\[\text{y}\ \text{=}\,\dfrac{\text{c(a-b)+a}}{{{\text{a}}^{\text{2}}}\text{-}{{\text{b}}^{\text{2}}}}\]
 

(iii) \[\dfrac{\text{x}}{\text{a}}\text{-}\dfrac{\text{y}}{\text{b}}\ \text{=}\ \text{0}\] and \[\text{ax+by}\ \text{=}\ {{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\]

Ans:

\[\dfrac{\text{x}}{\text{a}}\text{-}\dfrac{\text{y}}{\text{b}}\ \text{=}\ \text{0}\] or \[\text{bx-ay}\ \text{=}\ \text{0}\]

(1) \[\text{ax+by}\ \text{=}\ {{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\]

(2) On multiplying the equation (1) and (2) by b and a respectively, we get \[{{\text{b}}^{2}}\text{x-aby}\ \text{=}\ \text{0}\]

(3) \[{{\text{a}}^{\text{2}}}\text{x+aby}\ \text{=}\ {{\text{a}}^{\text{3}}}\text{+a}{{\text{b}}^{\text{2}}}\]

(4) On adding equation (3) and (4), we get \[{{\text{b}}^{2}}\text{x+}{{\text{a}}^{\text{2}}}\text{x}\ \text{=}\ {{\text{a}}^{\text{3}}}\text{+a}{{\text{b}}^{\text{2}}}\]

\[\text{x(}{{\text{b}}^{\text{2}}}\text{+}{{\text{a}}^{\text{2}}}\text{)}\ \text{=}\ \text{a(}{{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\text{)}\]

\[\text{x}\ \text{=}\ \text{a}\]

By using (1), we get

\[\text{b(a)-ay}\ \text{=}\ \text{0}\]

\[\text{ab-ay}\ \text{=}\ \text{0}\]

\[\text{ab}\ \text{=}\ \text{ay}\]

\[\text{y}\ \text{=}\ \text{b}\] 

(iv)

\[\text{(a-b)x+(a+b)y}\ \text{=}\,{{\text{a}}^{\text{2}}}\text{-2ab-}{{\text{b}}^{\text{2}}}\]

and

\[\text{(a+b)(x+y)}\ \text{=}\,{{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\]

Ans:

\[\text{(a-b)x+(a+b)y}\ \text{=}\,{{\text{a}}^{\text{2}}}\text{-2ab-}{{\text{b}}^{\text{2}}}\]

(1) \[\text{(a+b)(x+y)}\ \text{=}\,{{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\]

Or,

\[\text{(a+b)x+(a+b)y}\ \text{=}\ {{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\]

(2) On subtracting equation (2) from (1), we get \[\text{(a-b)x-(a+b)x}\ \text{=}\ \text{(}{{\text{a}}^{\text{2}}}\text{-2ab-}{{\text{b}}^{\text{2}}}\text{)-(}{{\text{a}}^{\text{2}}}\text{+}{{\text{b}}^{\text{2}}}\text{)}\]

\[\text{(a-b-a-b)x}\ \text{=}\ \text{-2ab-2}{{\text{b}}^{2}}\]

\[\text{-2bx}\ \text{=}\ \text{-2b(a+b)}\]

\[\text{x}\ \text{=}\ \text{a+b}\]

Using equation (1), we get 

\[\text{(a-b)(a+b)+(a+b)y}\ \text{=}\ {{\text{a}}^{\text{2}}}\text{-2ab-}{{\text{b}}^{\text{2}}}\]

\[{{\text{a}}^{2}}\text{-}{{\text{b}}^{2}}\text{+(a+b)y}\ \text{=}\ {{\text{a}}^{\text{2}}}\text{-2ab-}{{\text{b}}^{\text{2}}}\]

\[\text{(a+b)y}\ \text{=}\ \text{-2ab}\]

\[\text{y}\ \text{=}\ \dfrac{\text{-2ab}}{a+b}\]
 

(v) \[\text{152x-378y}\ \text{=}\ \text{-74}\] and \[\text{-378x+152y}\ \text{=}\ \text{-604}\]

Ans:

\[\text{152x-378y}\ \text{=}\ \text{-74}\]

\[\text{x}\ \text{=}\ \dfrac{\text{189y-37}}{\text{76}}\]

(1)

\[\text{-378x+152y}\ \text{=}\ \text{-604}\]

\[\text{-189x+76y}\ \text{=}\ \text{-302}\]

(2)

Substituting the value of \[\text{x}\] in equation (2), we get \[\text{-(189}{{\text{)}}^{\text{2}}}\text{y+189 }\!\!\times\!\!\text{ 37+(76}{{\text{)}}^{\text{2}}}\text{y}\ \text{=}\ \text{-302 }\!\!\times\!\!\text{ 76}\]

\[\text{189 }\!\!\times\!\!\text{ 37+302 }\!\!\times\!\!\text{ 76}\ \text{=}\ {{\text{(189)}}^{\text{2}}}\text{y-(76}{{\text{)}}^{\text{2}}}\text{y}\]

\[\text{6993+22952}\ =\ \text{(189-76)(189+76)y}\]

\[\text{29945}\ \text{=}\ \text{(113)(265)y}\]

\[\text{y}\ \text{=}\ \text{1}\]

From equation (1), we get

\[\text{x = }\dfrac{\text{189(1)-37}}{\text{76}}\ \text{=}\ \dfrac{\text{189-37}}{\text{76}}\ \text{=}\ \dfrac{\text{152}}{\text{76}}\]

\[\text{x}\ \text{=}\ \text{2}\]
 

8. ABCD is a cyclic quadrilateral that finds the angles of the cyclic quadrilateral.


Cyclic Quadrilateral


Cyclic Quadrilateral


Ans:

We know that the sum of the measures of opposite angles in a cyclic quadrilateral is \[\text{18}{{\text{0}}^{\bullet }}\]

Therefore,

\[\angle \text{A+}\angle \text{C}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

\[\text{4y+20-4x}\ \text{=}\ \text{18}{{\text{0}}^{\text{}}}\]

\[\text{4y-4x}\ \text{=}\ \text{16}{{\text{0}}^{\text{}}}\]

\[\text{x-y}\ \text{=}\ \text{-4}{{\text{0}}^{\text{}}}\]

(i) Also,

\[\angle \text{B+}\angle \text{D}\ \text{=}\ \text{18}{{\text{0}}^{\bullet }}\]

\[\text{3y-5-7x+5}\ \text{=}\ \text{18}{{\text{0}}^{\text{}}}\]

\[\text{3y-7x}\ \text{=}\ \text{18}{{\text{0}}^{\text{}}}\]

(ii) Multiplying equation (i) by \[3\] , we get \[\text{3x-3y}\ \text{=}\ -12{{\text{0}}^{\text{}}}\]

(iii) On adding equation (ii) and (iii), we get \[\text{3x-7x}\ \text{=}\ {{180}^{\bullet }}-12{{\text{0}}^{\text{}}}\]

\[\text{-4x}\ \text{=}\ \text{6}{{\text{0}}^{\text{}}}\]

\[\text{x}\ \text{=}\ -{{15}^{\text{}}}\]

By using equation (i), we get

\[\text{x-y}\ \text{=}\ -{{40}^{\text{}}}\]

\[\text{-15-y}\ \text{=}\ -{{40}^{\text{}}}\]

\[\text{y}\ \text{=}\ \text{-1}{{\text{5}}^{\text{}}}\text{+4}{{\text{0}}^{\text{}}}\ \text{=}\ \text{2}{{\text{5}}^{\text{}}}\]

\[\angle \text{A}\ \text{=}\ \text{4y+2}{{\text{0}}^{\bullet }}\ =\ 4({{25}^{\bullet }})+{{20}^{\bullet }}\ =\ {{120}^{\bullet }}\]

\[\angle \text{B}\ \text{=}\ 3\text{y-}{{\text{5}}^{\bullet }}\ =\ 3({{25}^{\bullet }})-{{5}^{\bullet }}\ =\ {{70}^{\bullet }}\]

\[\angle \text{C}\ \text{=}\ -4x\ =\ -4(-{{15}^{\bullet }})\ =\ {{60}^{\bullet }}\]

\[\angle \text{D}\ \text{=}\ \text{-7x+}{{\text{5}}^{\text{}}}\ \text{=}\ \text{-7(-1}{{\text{5}}^{\text{}}}\text{)+}{{\text{5}}^{\text{}}}\ \text{=}\ \text{11}{{\text{0}}^{\text{}}}\]

NCERT Solution Maths Class 10 Chapter 3 – An Overview

NCERT Solutions Class 10 Maths Chapter 3 Exercise 3.7 - Free PDF Download

Students can download the Class 10 Maths NCERT Ex 3.7 Solutions PDF to focus on understanding each type of sum covered in this chapter. The objective of Class 10 Maths Chapter 3 Exercise 3.7 NCERT Solutions PDF is to promote conceptual learning experience among the students of Class 10. The PDF contains a detailed explanation of every sum given in this exercise. You are marked for every step in the board exams, so there’s a good chance for you to score well if you practice these solutions. Hence, with Class 10 Maths Chapter 3 Exercise 3.7 NCERT Solutions students can prepare well for their upcoming examinations.

CBSE Class 10 Maths Exercise 3.7 Solutions are available for download for free of cost on Vedantu because we believe in quality education for all. These solutions will clear all your doubts. These solutions are prepared to give you an in-depth understanding of the concepts of this chapter. Linear equations in two variables are governed by several important concepts that have applications in higher mathematics as well.

Students of Class 10th preparing for their examinations should be careful while planning their study schedule. It requires an understanding of the syllabus and the weightage of each chapter to correctly plan your studies. Students should try to strengthen their strong points first and then bolster their weak points.

The mathematics syllabus is divided into 6 units. Each unit is important and connected to the other units. The weightage of each unit in the examination is different. Given below is the weightage of each unit.

Class 10th Maths Weightage Marks

Unit

Weightage Marks

Number System

06

Algebra

20

Coordinate Geometry

06

Geometry

15

Trigonometry

12

Mensuration

10

Statistics And Probability

11


The question paper of Class 10 is divided into four sections- Section A, B, C, and D. There are four different types of questions you will find in the question paper. These are- very short answer type, short answer type I, short answer type II, and long answer type questions. The weightage of these in the paper is given below.

  • 20 questions x 1 marks each: Very Short Answer type questions.

  • 6 questions x 2 marks each: Short Answer  type I questions.

  • 8 questions x 3 marks each: Short Answer type II questions.

  • 6 questions x 4 marks each: Long Answer type questions.

Benefits of Exercise 3.7 Class 10 Maths NCERT Solutions PDF

Exercise 3.7 Class 10 Maths consists of questions from the topic of linear equations in two variables. CBSE Class 10 Maths Exercise 3.7 Solutions PDF is designed with the aim to provide an easy understanding of the concepts. It contains a simple and logical explanation of each question. If you have doubts regarding any questions, you can download and refer to the NCERT Solutions for Class 10 Maths Chapter 3 Ex 3.7 PDF.

Class 10 Maths Chapter 3 Exercise 3.7 NCERT Solutions PDF is beneficial for students preparing for their upcoming examination. The benefits of Class 10 Maths Ex 3.7 Solutions PDF are as follows.

  • The solutions are prepared in a step-wise manner.

  • These solutions are prepared by the highly experienced teachers at Vedantu.

  • A detailed explanation of all questions provides an in-depth understanding of the concepts.

  • Every solution is prepared in accordance with the CBSE guidelines.

FAQs on NCERT Solutions for Class 10 Maths Chapter 3: Pair of Linear Equations in Two Variables - Exercise 3.7

1. What are the Basic Concepts Covered in Chapter 3 Pair of Linear Equations in Two Variables?

The basic concepts covered in Chapter 3 Pair of Linear Equations are discussed below.

Linear equation in two variables is of the form: 

ax + by + c = 0, where a, b and c are real numbers.

Any equation in two variables can be plotted on the coordinate plane. 

A pair of linear equation in two variables is of the form:

a1x + b1y + c1 = 0

a2x + b2y + c2 = 0

 Where,

a1, b1, c1, a2, b2 and c2 are real numbers.

The solution of a pair of linear equations in two variables can be derived using two methods:

  • Graphical method

  • Algebraic method

The graphical method is less convenient as it is not possible to represent non-integral coordinates.


Therefore we commonly use Algebraic methods in finding the solution:

It can be done using:

  1. Substitution Method - Substitute the value of one variable in terms of another variable.

  2. Elimination Method - Eliminate a single variable by making its coefficient equal and subtracting the equations.

  3. Cross-Multiplication Method.

2. What is the Revised Maths Syllabus for Class 10 Examinations?

The syllabus of class mathematics is vast and tests the student’s knowledge in a wide array of mathematical concepts and application-based problems. Students should keep in mind the syllabus during their preparations. Make sure that you are up to date with any changes in the syllabus and you prepare every chapter thoroughly.


The class 10 mathematics syllabus has a total of 16 chapters categorized into 6 units.

  • Chapter 1 - Real Numbers

  • Chapter 2 - Polynomials

  • Chapter 3 - Pair of Linear Equations in Two Variables

  • Chapter 4 - Quadratic Equations

  • Chapter 5 - Arithmetic Progressions

  • Chapter 6 - Lines (In two-dimensions)

  • Chapter 7 - Triangles

  • Chapter 8 - Circles

  • Chapter 9 - Constructions

  • Chapter 10 - Introduction to Trigonometry

  • Chapter 11 - Trigonometric Identities

  • Chapter 12 - Heights and Distances

  • Chapter 13 - Areas Related to Circles

  • Chapter 14 - Surface Areas and Volumes

  • Chapter 15 - Statistics

  • Chapter 16 - Probability

3. Which question is important in Optional Exercise 3.7 of Class 10 Maths?

There is no such thing as the most important question. All the questions designed for the students in Class 10 are prepared with keeping the overall understanding of the concepts in mind. Hence, it is important to solve all the questions with sincerity. Also from the examination point of view, any question may be set from any topic and hence it is important to prepare well for all of them. The difficulty level of each question might vary.

4. Is Exercise 3.7 of Class 10 Maths easy?

Practice makes Maths easy for any student. Once the student clearly grasps the basic concepts and learns the tricks to solve each question and the knowledge about the most plausible approach, only then will the student excel in Maths. Therefore, it is of utmost concern to learn the basics well and practice well for multiple types of questions. This particular exercise is a mix of different questions in terms of difficulty. 

5. What is the elimination method according to Chapter 3 of Class 10 Maths?

To produce an equation in one variable, you can either add or subtract the equations using the elimination technique. When the coefficients of one variable are opposites, the equations are added to delete the variable, and when the coefficients of one variable are equal, the equations are subtracted to eliminate the variable. This method is very useful and hence all the problems related to this method must be practised to have a clear understanding of the concepts of this method.

6. How to score good marks in Chapter 3 of Class 10 Maths? 

Tips: 

  • Refresh your memory on the fundamentals.

  • Recognize the concepts. Do not memorise the course material.

  • Understand the derivations and formulas and their applications.

  • Attempt to answer NCERT questions of Chapter 3 of Class 10 Maths.

  • Determine which chapters you are familiar with and which require more practice.

  • If you are having difficulty understanding a topic, you can seek the assistance of Vedantu to clear your doubts.

The solutions provided by Vedantu are free of cost and also available on Vedantu Mobile app.

7. What do you mean by a linear equation according to Chapter 3 of Class 10 Maths?

One way to think of it is that a linear equation is a mathematical equation in which each term has an exponent of one. This equation is referred to as a linear one because when you try to display the graph of the provided equation on an axes-based graph, you get a straight line as the result. It is an important topic and therefore you must learn the fundamentals well and also practice all the exercises given in the Chapter 3 of NCERT Textbook of Class 10 Maths.