3m(x-y)的3次方+27m的3次方(y-x)

问题描述:

3m(x-y)的3次方+27m的3次方(y-x)

=3m(x-y)³-27m³(x-y)
=3m(x-y)[(x-y)²-9m²]
=3m(x-y)(x-y+3m)(x-y-3m)