Question

9х^2-7(х+4)*(4-х)-(1-4Х)^2=15

Answer 1

9х^2-7(х+4)*(4-х)-(1-4Х)^2=15

9х^2-7(4x+16-x^2-4x)-(1-8x+16x^2)=15

9x^2-7(16-x^2)-1+8x-16x^2=15

-112+7x^2-1+8x-7x^2=15

8x=15+112+1=128

х=128/8=16