(x^2-16)/(x^2+8x+16)+ x/(x-4）
=(x-4)(x+4)/(x+4)^2+ x/(x-4）
=(x-4)/(x+4)+ x/(x-4）
=(x-4)^2/(x+4)(x-4)+ x(x+4)/(x-4)(x+4)
=[(x-4)^2+ x(x+4)]/(x-4)(x+4)
=(x^2-8x+16+x^2+4x)/(x-4)(x+4)
=(2x^2-4x+16)/(x-4)(x+4)
=2(x^2-2x+8)/(x-4)(x+4)
=2(x^2-2x+8)/(x^2-16)