已知xy=5,x-y=2,则代数式1/2x³-x²y²+1/2xy³的值为________

问题描述:

已知xy=5,x-y=2,则代数式1/2x³-x²y²+1/2xy³的值为________

1/2xy(x²-2xy+y²)=1/2xy(x-y)²=10