已知x-y=4,xy=-2,则-x³y+2x²y²-xy³的值为?
问题描述:
已知x-y=4,xy=-2,则-x³y+2x²y²-xy³的值为?
答
-x³y+2x²y²-xy³
=-xy(x²-2xy+y²
=-xy(x-y)²
=-(-2)×4²
=32