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
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