已知x+y=8,xy=12,求x²+y²的值

已知x+y=8,xy=12,求x²+y²的值

x²+y²
=(x+y)²-2xy
=8x8-2x12
=64-24
=40
希望能帮你忙,懂了请采纳,

x²+y²
=x²+2xy+y²-2xy
=（x+y）²-2xy
=64-24
=40

x²+y²=(x+y)²-2xy=64-24=40;