x-y=5,xy=6,则x^2y-xy^2=?,x^2y+xy^2=?加上理由!
问题描述：
x-y=5,xy=6,则x^2y-xy^2=?,x^2y+xy^2=?
加上理由!
答
x^2y-xy^2
=xy(x-y)
=6*5=30
xy(x+y)
=6*根号((x+y)^2)
=6*有号((x-y)^2+4xy)
=6*根号(25+4*6)
=6*7=42
或6*（-7）=-42