Question

please find the attached ​

Answer 1

3x - 4y = 10

On squaring both sides :

(3x-4y)² = 10² - (1)

We know that :

(a-b)² = a²+b²-2ab - (2)

On applying formulae of equation (2) in equation (1), we get :-

(3x)²+(4y)²-2×3x×4y = 100

9x²+16y²-24xy = 100 - (3)

xy = -1 -(4)

On putting value of equation (4) in equation (3), we get :

9x²+16y²-24×(-1) = 100

9x²+16y²+24 = 100

9x²+16y² = 100-24

9x²+16y² = 76