3x²y-3y²x+2xy²-2x²y,其中x=二分之一y=-1_数学解答

3x²y-3y²x+2xy²-2x²y,其中x=二分之一y=-1

人气：197 ℃　时间：2020-03-21 20:27:53

解答

3x²y-2x²y-3y²x+2xy²
=x²y-xy²
=xy(x-y)
x=-1
y=-2
3x²y-2x²y-3y²x+2xy²
=x²y-xy²
=xy(x-y)
=2(-1+2)
=2