因子分解

解决方案:

2x？-x？-5x-2

=2x？-x？2x-2x-x-2

=﹙2x？-2x﹚-﹙x？+x﹚-﹙2x+2﹚

=2x(x？-1﹚-x(x+1)-2(x+1)

=(x+1)[2x(x-1)-x-2]

=(x+)(x-2)(2x+1)