先化简再求值:(3x^2-xy^2)-3(x^2y-2xy^2),其中x=1/2,y=-1/3
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发布时间：2024-10-04 20:16
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热心网友
时间：2024-10-04 21:53
=3x^2-xy^2-3x^2y+6xy^2
=3x^2-3x^2y+5xy^2
=3x(x-y)+5xy^2
=3*(1/2)(1/2+1/3)+5*(1/2)(-1/3)^2
=1+5/18
=23/18
