已 知x加y等于3，xy等于负7 x的平方减xy加y的平方等于多少？

Question

如题所述

Answer 1

x²-xy+y²
=(x²+2xy+y²)-3xy
=(x+y)²-3xy
=3²-3·(-7)
=30本回答被提问者采纳

Answer 2

x²-xy+y²
=（x+y）²-3xy
=9-3×(-7)
=9+21
=30