(x+2)(x^2+5x-10)-(x+2)^2(x-1),其中x=1.5
问题描述:
(x+2)(x^2+5x-10)-(x+2)^2(x-1),其中x=1.5
答
(x+2)(x^2+5x-10)-(x+2)^2(x-1)=(x+2)[(x^2+5x-10)-(x+2)(x-1)]=(x+2)[(x^2+5x-10)-(x^2+x-2)]=(x+2)(4x-8)=4(x+2)(x-2)=4(x^2-4)将x=1.5代入,得原式=4×(1.5^2-4)=4×(2.25-4)=-7