Question

Pls help with this sum^^^

Answer 1

square on both the side in the first equation and substitute the value of xy in that and bring the multiplied xy term with the rhs then your answer will be 160.
(3x+4y)^2=(16)^2
9x^2+16y^2+24xy =256
9x^2+16y^2+96=256....(sub the value of xy)
9x^2+16y^2=160