已知xy²=-2,求-xy(x²y的五次方-xy³-y)的值
问题描述:
已知xy²=-2,求-xy(x²y的五次方-xy³-y)的值
答
-xy(x²y的五次方-xy³-y)
=-x³y^6+x²y^4+xy²
=-(xy²)³+(xy²)²+xy²
=-(-2)³+(-2)²+(-2)
=-8+4-2
=-6