Question

If (x^2-y^2,x+y)=(-7,7) then the value of x+2yis?

Answer 1

From,

(x^2-y^2, x+y)=(-7, 7)

We get,

x + y = 7  ----------eq1

x^2 - y^2 = -7                                      [$a^{2} - b^{2} = (a+b)(a-b)$]

(x + y) (x - y) = -7

From eq1

7(x - y) = -7

x - y = -49 -----------eq2

Adding eq1 & eq2

2x = -42

x = -21

Putting x = -21 in eq1

-21 + y = 7

y = 28

x + 2y = -21 + 2 x 28 = -21 + 56 = 35 : Ans

Hope I helped