Question

9$x^{2}$ - 7(x+4)(4-x) - (1-4x)$^{2}$ = 15

Answer 1

9x^2 - 7*(16-x^2)-(1-8x+16x^2)=15
9x^2 -112+7x^2-1+8x-16x^2-15=0
8x-128=0
x+16=0
х=-16

Answer 2

там не х^2, там 9x^2