Answer
Verified
420.3k+ views
Hint: For solving this question we will directly apply one formula and do the multiplication of the corresponding terms with each other and then solve for the correct answer.
Complete step-by-step answer:
Given:
We have to find the result of $\left( x+7y \right)\times \left( 7x-y \right)$ . Where $x$ and $y$ are variables.
Now, we will use the formula written below in this question to get the correct answer. We know that we can multiply any two variables with each other. Now, look at the formula given below:
$\left( a+b \right)\times \left( c+d \right)=ac+ad+bc+bd...........\left( 1 \right)$ .
Now, we will substitute $a=x$ , $b=7y$ , $c=7x$ and $d=-y$ . Then,
$\begin{align}
& \left( x+7y \right)\times \left( 7x-y \right) \\
& \Rightarrow 7{{x}^{2}}-xy+49xy-7{{y}^{2}} \\
& \Rightarrow 7{{x}^{2}}+48xy-7{{y}^{2}} \\
\end{align}$
Thus, from the above result, we can say that, $\left( x+7y \right)\times \left( 7x-y \right)=7{{x}^{2}}+48xy-7{{y}^{2}}$ . Now, we can select the correct option from the given options. Then, we can say that (a) is the correct option.
Hence, option (a) is the correct option.
Note: The question is very easy to solve and we can solve it without any formulae also, where we can easily do the calculations just like we multiply any two numerical values we can multiply variables with one another and then do the arithmetic calculations like we can add and subtract the coefficient of same variables as per their sign. One more important point is that the student should take care of any calculation mistake while solving the question to get the correct answer.
Complete step-by-step answer:
Given:
We have to find the result of $\left( x+7y \right)\times \left( 7x-y \right)$ . Where $x$ and $y$ are variables.
Now, we will use the formula written below in this question to get the correct answer. We know that we can multiply any two variables with each other. Now, look at the formula given below:
$\left( a+b \right)\times \left( c+d \right)=ac+ad+bc+bd...........\left( 1 \right)$ .
Now, we will substitute $a=x$ , $b=7y$ , $c=7x$ and $d=-y$ . Then,
$\begin{align}
& \left( x+7y \right)\times \left( 7x-y \right) \\
& \Rightarrow 7{{x}^{2}}-xy+49xy-7{{y}^{2}} \\
& \Rightarrow 7{{x}^{2}}+48xy-7{{y}^{2}} \\
\end{align}$
Thus, from the above result, we can say that, $\left( x+7y \right)\times \left( 7x-y \right)=7{{x}^{2}}+48xy-7{{y}^{2}}$ . Now, we can select the correct option from the given options. Then, we can say that (a) is the correct option.
Hence, option (a) is the correct option.
Note: The question is very easy to solve and we can solve it without any formulae also, where we can easily do the calculations just like we multiply any two numerical values we can multiply variables with one another and then do the arithmetic calculations like we can add and subtract the coefficient of same variables as per their sign. One more important point is that the student should take care of any calculation mistake while solving the question to get the correct answer.
Recently Updated Pages
The branch of science which deals with nature and natural class 10 physics CBSE
The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths
Define absolute refractive index of a medium
Find out what do the algal bloom and redtides sign class 10 biology CBSE
Prove that the function fleft x right xn is continuous class 12 maths CBSE
Find the values of other five trigonometric functions class 10 maths CBSE
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Difference Between Plant Cell and Animal Cell
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
What organs are located on the left side of your body class 11 biology CBSE
Write an application to the principal requesting five class 10 english CBSE
What is the type of food and mode of feeding of the class 11 biology CBSE
Name 10 Living and Non living things class 9 biology CBSE