x+y=2,xy=-(1/2)구 x(x+y)&\#178;(1-y)-x(y+x)²값어치

x+y=2,xy=-(1/2)구 x(x+y)&\#178;(1-y)-x(y+x)²값어치

x(x+y)²(1-y)-x(y+x)²
=x(x+y)²(1-y-1)
=-xy(x+y)²
=-(-1/2)×2²
=1/2×4
=2