Get interactive courses taught by top teachers

Last updated date: 20th Sep 2023

•

Total views: 144.3k

•

Views today: 10.83k

A** differential equation **is a mathematical equation that connects the derivatives of a function. The functions are usually used to represent physical quantities, the derivatives are used to represent their rates of change, and the equation is used to define a relationship between the two.

JEE Main Maths Chapter-wise Solutions 2023-24

Differential Equations

Differential Equation And Its Types

Partial Differential Equations

Partial Derivative

Linear Differential Equations

Homogeneous Differential Equations

A differential equation is an equation which contains one or more terms and the derivatives of one dependent variable with respect to the other independent variable

$\dfrac{dy}{dx}=f(x)$, Where ‘x’ is an independent variable and ‘y’ is a dependent variable.

$\dfrac{dy}{dx} = \sin x$

$\dfrac{d^2y}{dx^2} + k^2y = 0$

$\dfrac{d^2y}{dt^2} + \dfrac{d^2x}{dt^2} = x$

$\dfrac{d^3y}{dx^3} + x\left(\dfrac{dy}{dx}\right) - 4xy = 0$

$\dfrac{rdr}{d\theta} + \cos \theta = 5$

The highest order of the derivative appearing in a differential equation is the order of the equation.

Example: $2x + \dfrac{dy}{dx} = 1$ order of a differential equation is equal to 1.

$\dfrac{d^{2} y}{dx} + \cos x = \dfrac{1}{2}$ order of a differential equation is equal to 2.

$\dfrac{d^{3} y}{dx} + 2\dfrac{d^{2} y}{dx} + x^{3} + 6 = 0$ order of a differential equation is equal to 3.

A first-order differential equation is one where f(x, y) is a function of two variables defined in the XY-plane. All linear equations are in the first-order form of derivatives. It only has the first derivative, as in $\dfrac{dy}{dx}$. As you can see in the first example, it's a one-degree first-order differential equation.

$\dfrac{dy}{dx} = f(x, y) = y^\prime$

A second-order linear differential equation is an equation of the form that is linear in y and its derivatives.

$\dfrac{d}{dx} \left(\dfrac{dy}{dx}\right) = \dfrac{d^2y}{dx^2} = f^{\prime \prime}(x) = y^{\prime \prime}$

The highest power of the highest order derivative involved in the given differential equation is the degree of the differential equation.

Example: $\dfrac{dy}{dx})^{2} +\dfrac{d^{2}y}{dx} + 1 = 0$ The highest degree derivative in this equation has a power of one. As a result, the order of the differential equation is equal to 1.

$\dfrac{dy}{dx} + 1 = 0$, degree of a differential equation is equal to 1

$(y^{\prime \prime \prime})3 + 2y^{\prime \prime} + 10y^\prime - 4 = 0$, degree of a differential equation is equal to 3

Note: It is not always necessary for the degree and order of a differential equation to be equal, but they must both be positive.

Homogeneous Differential Equations

Nonhomogeneous Differential Equations

Ordinary differential equations

Partial differential equations

Nonlinear differential equations

Linear Differential Equations

A homogeneous differential equation is a differential equation in which all of the terms have the same degree.

$P(x,y)dx + Q(x,y)dy = 0$ is a general representation, where P(x,y) and Q(x,y) are homogeneous functions of the same degree.

Examples: $y + 2x\left(\dfrac{dy}{dx}\right) = 0$ is a homogeneous differential equation of degree equal to 1.

$x^2 + y^4\left(\dfrac{dy}{dx}\right) = 0$ is a homogeneous differential equation of degree equal to 4.

A homogeneous differential equation is a differential equation in which all of the terms have different degrees.

Example: $y\dfrac{dy}{dx} + y^2 + 2x = 0$ is a non-homogeneous differential equation.

A linear differential equation is a differential equation of the form $\dfrac{dy}{dx} + Py = Q$.

Where P and Q are numeric constants or functions in x. It is made up of a y and a y derivative. The differential equation is called the first-order linear differential equation because it is a first-order differentiation.

General solution of differential equation is, $y \times (I.F) = \int{Q(I.F)}dx + c$ where, I.F (integrating factor) $= e^{\int p dx}$

The function and its derivatives are involved in an ordinary differential equation. It only has one independent variable and one or more derivatives with respect to the variable. The ordinary differential equation can be homogeneous or nonhomogeneous. The general form of an $n^{th}$ order ordinary differential equation is as follows:

Example: $\dfrac{d^2y}{dx^2} + \dfrac{dy}{dx} = y \sin x$

Differential equations that have derivatives with respect to more than one independent variable are called Partial differential equations.

Example: $\dfrac{\partial u}{\partial x}+\dfrac{\partial u}{\partial t}=0$

The solution of a differential equation is a function that satisfies its solution.

A general solution is one that contains as many arbitrary constants as the order of the differential equation.

A particular solution is a solution that is free of arbitrary constants.

The solution to the differential equation can be found using two methods.

Variable Separable method

Integrating factor

The first-order differential equation is of the form $\dfrac{dy}{dx} = F(x,y)$

Where F(x, y) can be written as h(x)g(y), with h(x) being a function of x and g(x) being a function of y. The equation is then known as a variable separable differential equation. $\dfrac{dy}{dx} = h(x)g$ is the differential equation's form (x).

When the differential equation is of the form $\dfrac{dy}{dx} + p(x)y = q(x)$, the integrating factor method is used. $y^\prime + P(x)y = Q$ is a first-order differential equation (x). An equation containing partial or ordinary derivatives of an unknown function is referred to as a higher-order differential equation. It is possible to represent it in any order.

There are an infinite number of solutions to the differential equation. Because the process of solving a differential equation is referred to as integrating a differential equation.

A differential equation solution is an expression for the dependent variable that satisfies the differential equation in terms of the independent variable.

The general solution is one that contains as many arbitrary constants as possible. The resulting solution is called a Particular Solution when the arbitrary constants in the general solution of the differential equation are given particular values.

A first-order differential equation is obtained by eliminating one arbitrary constant.

A second-order differential equation is obtained by eliminating two arbitrary constants, and so on.

Differential equations are equations that have an independent variable, a dependent variable, and the derivative of the dependent variable with respect to the independent variable.

Ordinary differential equations have a single independent variable, while partial differential equations have more than one independent variable and their partial derivative.

Consider equation $\dfrac{dy}{dx} = x^2y + 2y$

Step 1: Divide the above differential equation w.r.t y.

$\dfrac{1}{y}\left(\dfrac{dy}{dx}\right) = \dfrac{1}{y}\times y(x^2 + 2)$

$\dfrac{1}{y}\left(\dfrac{dy}{dx}\right) =(x^2 + 2)$

Both y and x are variables, so we rewrite the equation as

$\dfrac{dy}{y} = (x^2 + 2)dx$

Step 2: Now L.H.S. should be integrated both in terms of y and x.

$\int{\dfrac{1}{y}dx} = \int{(x^2 + 2)}dx$

Step 3: On integrating, we get:

$\text{log }y = \dfrac{x^3}{3} + 2x + c$

Differential equations are used in various fields, including applied mathematics, science, and engineering. Apart from technical applications, they are also used to solve a variety of real-world issues. In real life, ordinary differential equations are used to calculate the movement or flow of electricity, the motion of an object to and fro, such as a pendulum, and to explain thermodynamics concepts. In medical terms, they're also used to visualize the progression of diseases in graphical form. Differential equations can be used to describe mathematical models such as population growth or radioactive decay.

For derivatives, use the following notations.

$\dfrac{dy}{dx} = y^\prime$

$\dfrac{d^2y}{dx^2} = y^{\prime\prime}$

$\dfrac{d^3y}{dx^3} = y^{\prime\prime\prime}$

Example 1: Form the differential equation of the family of curves, y = mx.

Ans: Given: $y = mx$

Differentiating both sides of the equation we get,

$\dfrac{dy}{dx} = m$, because m is a constant

Substitute the value of m in the given equation, we get

$y = \dfrac{dy}{dx}x$

$y - \dfrac{dy}{dx}x = 0$

Or

$y - y^\prime x = 0$

Example 2: Check whether the differential equation, $(x+y)\dfrac{dy}{dx} = x - 2y$ is homogeneous.

Ans: Given $(x+y)\dfrac{dy}{dx} = x - 2y$ is a homogeneous equation,

The given equation can be written as $\dfrac{dy}{dx} = \dfrac{x-2y}{x+y}$

As it is an homogeneous equation it can be written as,

$F(x,y) = \dfrac{x-2y}{x+y}$

Let a be a constant, so

$F(ax,ay) = \dfrac{ax-2ay}{ax+ay}$

$F(ax,ay) = \dfrac{x-2y}{x+y}a^0$

$F(ax,ay) = a^0 F(x,y)$

Since this function is homogeneous, so is the differential equation.

Example 3: Find the general solution of the differential equation, $\dfrac{dy}{dx} = \dfrac{x-1}{2+y}$ where $(y \ne 2)$

Ans: Given, $\dfrac{dy}{dx} = \dfrac{x-1}{2+y}$

On simplifying we get,

$(2+y)dy = (x-1)dx$

$\int{(2+y)dy} = \int{(x-1)dx}$

$2y+\dfrac{y^2}{2} = \dfrac{x^2}{2}-x+c$

$4y+y^2-x^2+2x=c$

1. If $x dy = y (dx + y dy)$, $y > 0$ and $y (1) = 1$, then $y (-3)$ is equal to ______.

Ans: Given, $x dy = y (dx + y dy)$

Given equation can be written as,

$x dy = y dx + y^2 dy$

Multiplying with -1 and rearranging we get,

$y dx - x dy = -{y^2} dy$

$\dfrac{y dx - x dy}{y^2} = -dy$

Integrating both the sides we get,

$\dfrac{x}{y} = -y + c$

Given x = 1, and y = 1

$1=-1+c$

$c=2$

Substituting we get,

$\dfrac{x}{y} = -y + 2$

To find y at x = -3, we get,

$-\dfrac{3}{y}=-y+2$

$\Rightarrow -3=-y^{2}+2 y$

$\Rightarrow y^{2}-2 y-3=0$

$\Rightarrow y^{2}-3 y+y-3=0$

$\Rightarrow y(y-3)+(y-3)=0$

$\Rightarrow(y+1)(y-3)=0$

$\Rightarrow y=-1$ or $y=3$

2. If ${{dy} \over {dx}} = {{{2^{x + y}} - {2^x}} \over {{2^y}}}$, y(0) = 1, then y(1) is equal to ______.

Ans: Given $\dfrac{d y}{dx}=\dfrac{2^{x+y}-2^{x}}{2^{y}}$

The given equation can be written as,

$2^{y} \dfrac{d y}{dx}=2^{x}\left(2^{y}-1\right)$

Integrating on both the sides, we get

$\int \dfrac{2^{y}}{2^{y}-1} d y=\int 2^{x} dx$

$\dfrac{\ln \left(2^{y}-1\right)}{\ln 2}=\dfrac{2^{x}}{\ln 2}+c$

$\Rightarrow \log _{2}\left(2^{y}-1\right)=2^{x} \log _{2} e+c$ —(1)

As $y(0)=1$

$\Rightarrow 0=\log _{2} e+c$

$C=-\log _{2} e$

Substitute in equation (1), we get

$\Rightarrow \log _{2}\left(2^{y}-1\right)=\left(2^{x}-1\right) \log _{2} e$

Put $x=1$, $\log _{2}\left(2^{y}-1\right)=\log _{2} e$

$2^{y}=e+1$

Hence, $y=\log _{2}(e+1)$

3. If a curve passes through the origin and the slope of the tangent to it at any point (x, y) is $\dfrac{d y}{dx}=\dfrac{(x-2)^{2}+y+4}{x-2}$, then this curve also passes through the point ______.

Ans: Given, $\dfrac{d y}{dx}=\dfrac{(x-2)^{2}+y+4}{x-2}$ and as the curve passes through the origin we can say that $y(0)=0$

$\dfrac{d y}{dx}-\dfrac{y}{x-2}=(x-2)+\dfrac{4}{x-2}$

$\Rightarrow I.F=e^{-\int \frac{1}{x-2} dx}=\dfrac{1}{x-2}$

Hence the solution of D.E is

$\Rightarrow y \cdot \dfrac{1}{x-2} = \int \dfrac{1}{x-2}\left((x-2) + \dfrac{4}{x-2}\right) \cdot dx$

$\Rightarrow \dfrac{y}{x-2}=x-\dfrac{4}{x-2}+c$

Now, at $x=0, y=0 \Rightarrow c=-2$

On substituting the value of c in the above equation we get,

$y=x(x-2)-4-2(x-2)$

$\Rightarrow y=x^{2}-4 x$

Hence the curve passes through $(5,5)$

1. Solve, $x(\dfrac{dy}{dx}) + y =y^{2logx}$

Ans: $\dfrac{1}{xy} = \dfrac{1}{x}logx + \dfrac{1}{x} + c$

2. Solve the differential equation: $\dfrac{dy}{dx} = (e^x + 1)y$

Ans: $log|y| =ex + x + c$

3. Solve $\left(x tan \dfrac{y}{x}-ysec^2 \dfrac{y}{x}\right)dx-x\sec^{2} \dfrac{y}{x}dy=0$

Ans: $\dfrac{xtany}{x} = c$

We can conclude that a differential equation is defined as an equation that contains the derivative or derivatives of the dependent variable with respect to the independent variable. We also discussed differential equation formulas and various methods for solving differential equations using basic differential equation formulas. Students can carefully read through the** Concepts, Definitions, and Questions in the PDFs** also, which are also free to download and understand the concepts used to solve these questions which is extremely beneficial in the exams.

These study materials will aid you in comprehending Differential Equations, ensuring a solid foundation for further mathematical pursuits.

Access a curated collection of study materials and tips to excel in JEE Main and Advanced 2023-24, helping you prepare effectively for these prestigious engineering entrance exams.

See More

JEE Main 2023 January and April Session exam dates and revised schedule have been announced by the NTA. JEE Main 2023 January and April Session will now be conducted on 24-Jan-2023 to 31-Jan-2023 and 6-Apr-2023 to 12-Apr-2023, and the exam registration closes on 12-Jan-2023 and Apr-2023. You can check the complete schedule on our site. Furthermore, you can check JEE Main 2023 dates for application, admit card, exam, answer key, result, counselling, etc along with other relevant information.

See More

View all JEE Main Exam Dates

Application Form

Eligibility Criteria

Reservation Policy

Admit Card

Exam Centres

NTA has announced the JEE Main 2023 January session application form release date on the official website https://jeemain.nta.nic.in/. JEE Main 2023 January and April session Application Form is available on the official website for online registration. Besides JEE Main 2023 January and April session application form release date, learn about the application process, steps to fill the form, how to submit, exam date sheet etc online. Check our website for more details. April Session's details will be updated soon by NTA.

It is crucial for the the engineering aspirants to know and download the JEE Main 2023 syllabus PDF for Maths, Physics and Chemistry. Check JEE Main 2023 syllabus here along with the best books and strategies to prepare for the entrance exam. Download the JEE Main 2023 syllabus consolidated as per the latest NTA guidelines from Vedantu for free.

See More

Download full syllabus

Download full syllabus

View JEE Main Syllabus in Detail

JEE Main 2023 Study Materials: Strengthen your fundamentals with exhaustive JEE Main Study Materials. It covers the entire JEE Main syllabus, DPP, PYP with ample objective and subjective solved problems. Free download of JEE Main study material for Physics, Chemistry and Maths are available on our website so that students can gear up their preparation for JEE Main exam 2023 with Vedantu right on time.

See More

All

Mathematics

Physics

Chemistry

See All

Download JEE Main Question Papers & Answer Keys of 2022, 2021, 2020, 2019, 2018 and 2017 PDFs. JEE Main Question Paper are provided language-wise along with their answer keys. We also offer JEE Main Sample Question Papers with Answer Keys for Physics, Chemistry and Maths solved by our expert teachers on Vedantu. Downloading the JEE Main Sample Question Papers with solutions will help the engineering aspirants to score high marks in the JEE Main examinations.

See More

In order to prepare for JEE Main 2023, candidates should know the list of important books i.e. RD Sharma Solutions, NCERT Solutions, RS Aggarwal Solutions, HC Verma books and RS Aggarwal Solutions. They will find the high quality readymade solutions of these books on Vedantu. These books will help them in order to prepare well for the JEE Main 2023 exam so that they can grab the top rank in the all India entrance exam.

See More

See All

JEE Main 2023 free online mock test series for exam preparation are available on the Vedantu website for free download. Practising these mock test papers of Physics, Chemistry and Maths prepared by expert teachers at Vedantu will help you to boost your confidence to face the JEE Main 2023 examination without any worries. The JEE Main test series for Physics, Chemistry and Maths that is based on the latest syllabus of JEE Main and also the Previous Year Question Papers.

See More

NTA is responsible for the release of the JEE Main 2023 January and April Session cut off score. The qualifying percentile score might remain the same for different categories. According to the latest trends, the expected cut off mark for JEE Main 2023 January and April Session is 50% for general category candidates, 45% for physically challenged candidates, and 40% for candidates from reserved categories. For the general category, JEE Main qualifying marks for 2021 ranged from 87.8992241 for general-category, while for OBC/SC/ST categories, they ranged from 68.0234447 for OBC, 46.8825338 for SC and 34.6728999 for ST category.

See More

NTA will release the JEE Main 2023 January and April sessions exam dates on the official website, i.e. {official-website}. Candidates can directly check the date sheet on the official website or https://jeemain.nta.nic.in/. JEE Main 2023 January and April sessions is expected to be held in February and May. Visit our website to keep updates of the respective important events of the national entrance exam.

See More

Rank List

Counselling

Cutoff

JEE Main 2023 state rank lists will be released by the state counselling committees for admissions to the 85% state quota and to all seats in IIT colleges. JEE Main 2023 state rank lists are based on the marks obtained in entrance exams. Candidates can check the JEE Main 2023 state rank list on the official website or on our site.

Want to know which Engineering colleges in India accept the JEE Main 2023 scores for admission to Engineering? Find the list of Engineering colleges accepting JEE Main scores in India, compiled by Vedantu. There are 1622 Colleges that are accepting JEE Main. Also find more details on Fees, Ranking, Admission, and Placement.

See More

FAQ

**1. In Calculus, What is a Differential Equation?**

A differential function is an equation that contains the derivative of a function. A differential equation is defined as an equation that involves the derivative (derivatives) of the dependent variable with respect to the independent variable (variables). A differential equation also contains derivatives of varying orders and degrees.

**2. How Do I Determine the Order and Degree of Differential Equations?**

A differential equation's order is the highest order of the derivative appearing in the equation. The degree of the differential equation is the exponent of the equation's highest ordered derivative. Consider the following differential equations:

$\dfrac{dy}{dx}=e^x$ highest derivative is 1

$\dfrac{d^4y}{dx^4} + y = 0$ highest derivative is 4

$\dfrac{d^3y}{dx^3} + x^2\left(\dfrac{d^2y}{dx^2}\right) = 0$ highest derivative is 3

**3. What Exactly is a Partial Differential Equation?**

A partial differential equation is a mathematical equation that contains two or more independent variables, an unknown function, and partial derivatives of the unknown function with respect to independent variables. When a partial differential equation is substituted into an equation, the solution is a function that solves the equation or, in other words, turns it into an identity. A solution is said to be general if it contains all of the particular solutions to the equation in question.