先化简再求值2(x+4)^2-(X+5)^2-(x+3)(x-3) x=-2

分类: 作业答案 • 2021-12-19 15:04:57

问题描述：

答

原式=2(x²+8x+16)-(x²+10x+25)-(x²-9)
=2x²+16x+32-x²-10x-25-x²+9
=6x+16
=6*(-2)+16
=4