已知x+y=-3 求(2x²+xy+3y²)-(x²-xy+2y²)的值
4个回答
(2x²+xy+3y²)-(x²-xy+2y²)
=2x²+xy+3y²-x²+xy-2y²
=x²+2xy+y²
=(x+y)²
=3²
=9
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