已知xy^2=-2,求-xy(x^2y^5-xy^3-y)的值.

问题描述:

已知xy^2=-2,求-xy(x^2y^5-xy^3-y)的值.

-xy(x^2y^5-xy^3-y)
=-(xy^2)^3+(xy^2)^2+xy^2
=-(-2)^3+4-2
=8+4-2
=10