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已知x=2,y=3,求3xy(xy-xy^2+x^2y)-xy^2(2x^2-3xy+2x)
人气:283 ℃ 时间:2020-03-10 10:52:30
解答
3xy(xy-xy^2+x^2y)-xy^2(2x^2-3xy+2x)
=3x²y²-3x²y³+3x³y²-2x³y²+3x²y³-2x²y²
=5x²y²+x³y²
=5×4×9+8×9
=180+72
=252
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