已知2x+y+4,xy=2,求-4x²y²-y³x-4x³y的值

已知2x+y+4,xy=2,求-4x²y²-y³x-4x³y的值
已知2x+y+4,xy=2,求-4x²y²-y³x-4x³y的值

已知2x+y+4,xy=2,求-4x²y²-y³x-4x³y的值
= -xy(y²+4xy+4x²)
= -xy(2x+y)²
= -2×4²
= -32

解
-4x²y²-y³x-4x³y
=-xy(4xy+y²+4x²)
=-xy(2x+y)²
=-2×(4²)
=-32