Question

1. If 3x+4y=16 and xy=4,find the value of 9x2+16y2

Answer 1

We know that (a+b)^2=a2+2ab+b2------------------------------ Here a =3x and b=4y------------------------------------------------- Therefore (3x+4y)^2=(3x)^2+2×3x×4y+(4y)^2---------------- => 16^2=9x2+24xy+16y2--------------------------'------------------ => 256=9x2+16x2+(24x4)------------------------------------------- =>9x2+16x2=256-96=160-------(answer)------------------------hope it helps u!!!Pls thank!!!!!