已知A=2x^2-3xy+2y^2,B=x^2+xy-3y^2,
求(1)A-B
(2)若2A-3B+C=0,求C
人气:481 ℃ 时间:2019-11-15 06:32:39
解答
(1)A-B= 2x^2-3xy+2y^2-(x^2+xy-3y^2)=2x^2-3xy+2y^2-x^2-xy+3y^2=x^2-4xy+5y^2(2)2A-3B+C=0即:2(2x^2-3xy+2y^2)-3(x^2+xy-3y^2)+C=0C=3(x^2+xy-3y^2)-2(2x^2-3xy+2y^2)C=3x^2+3xy-9y^2-4x^2+6xy-4y^2C=-x^2...
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