Question

初二数学问题，题目请看详细提问

计算：[x(x²y²-xy)-y（x²-x^3y）]÷3x²y

Answer 1

[x(x²y²-xy)-y（x²-x^3y）]÷3x²y
=(x^3y²-x²y-x²y+x^3y²)÷3x²y
=(2x^3y²-2x²y)÷3x²y
=(2x²y×xy-2x²y)÷3x²y
=2/3(xy-1)

追问

能告诉我你的=(2x²y×xy-2x²y)÷3x²y
里的xy从哪里来的？

Answer 2

(2x^3y^2-2x^2y)/3x^2y=-2/3+2/3xy=2/3(1+xy)