已知x+y=2,xy=1/2,求x³y+2x²y²+xy³
问题描述：
已知x+y=2,xy=1/2,求x³y+2x²y²+xy³
答
原式=0.5X~2+XY+0.5Y~2
=(0.5X+0.5Y)*(X+Y)
=0.5*4=2
答
x³y+2x²y²+xy³
=xy(x²+2xy+y²)
=xy(x+y)²
=1/2(2)²
=2