2x平方+(-x平方+3xy+2y平方)-(x平方-xy+2y平方)
=2x^2-x^2+3xy+2y^2-x^2+xy-2y^2
=4xy
=4*(-1/2)*3
=-6
2x平方+(-x平方+3xy+2y平方)-(x平方-xy+2y平方)其中x-1/2,y=3
2x平方+(-x平方+3xy+2y平方)-(x平方-xy+2y平方)其中x-1/2,y=3
数学人气:203 ℃时间:2019-12-11 00:07:05
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