已知:A=4x²-4xy+y²,B=x²+xy-5y²,求(3A-2B)-(2A+B)的值.
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已知:A=4x²-4xy+y²,B=x²+xy-5y²,求(3A-2B)-(2A+B)的值.
已知:A=4x²-4xy+y²,B=x²+xy-5y²,求(3A-2B)-(2A+B)的值.
已知:A=4x²-4xy+y²,B=x²+xy-5y²,求(3A-2B)-(2A+B)的值.
(3A﹣2B)﹣(2A+B)
=3A﹣2B﹣2A﹣B
=A﹣3B,
将A、B代入,即得:
=4x^2﹣4xy+y^2﹣3(x^2+xy﹣5y^2)
=4x^2﹣4xy+y^2﹣3x^2﹣3xy+15y^2
=x^2﹣7xy+16y^2.