帮忙做一道题。[2x--1]-4[X+1][x--2]

原式=2x+1-(4x+4)(x+2)
=2x+1-4X^2-12x-8
=-10X-4X^2-7

[2x-1]-4[x+1][x-2]
=2x-1-4[x^2-x-2]
=2x-1-[4x^2-4x-8]
=2x-1-4x^2+4x+8
=-4x^2+6x+7

[2x-1]-4[x+1][x-2]
=2x-1-4[x^2-x-2]
=2x-1-[4x^2-4x-8]
=2x-1-4x^2+4x+8
=-4x^2+6x+7

这么简单的题都不会，太懒了吧。不自己动脑筋，将来还期望什么呢？