Question

If the 3x-7y =10 and 4y =-1 so find the value of 9x2+49y2

Answer 1

$\textbf{Answer}$


We are given,
$\textbf{3x - 7y = 10}$ ----(1)
$\textbf{4y = - 1}$ ----------(2)

We need to find the value of,
$\textbf{9x^2 + 49y^2 = ?}$

Lets calculate y and y^2 by using equation (2),
4y = - 1

=> $\textbf{y = - 1/4}$

=> y^2 = (- 1/4)^2

=> $\textbf{y^2 = 1/16}$

Lets put the value of y in equation (1) and find out the value of x and x^2,

3x - 7y = 10

=> 3x - 7(- 1/4) = 10

=> 3x + 7/4 = 10

=> 3x = 10 - (7/4)

=> 3x = 33/4

=> x = (33) / (3×4)

=> $\textbf{x = 11/4}$

=> $\textbf{x^2 = 121/16}$

So lets find the value of 9x^2 + 49y^2,

9x^2 + 49y^2 = 9(121/16) + 49(1/16)

=> 9x^2 + 49y^2 = 68.06 + 3.06

=> $\textbf{9x^2 + 49y^2 = 71.12}$


$\textbf{Hope My Answer Helps}$

$\textbf{Thanks}$