1.x(x+1)+12=(x+1)(x+3)x²+x+12=x²+4x+3x9=3xx=32.(x-4)²-(x-4)(x-8) =12x²-8x+16-(x²-12x+32)=12x²-8x+16-x²+12x-32=124x-16=12x=7 3.(a²-2ab+b²）²-16=(a-b)&#...错了吧 是=(a-b-4)(a-b+4)对，很不好意思，打错了。.(a²-2ab+b²）²-16=(a-b)²-4²=(a-b-4)(a-b+4)