0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=?

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0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=?0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=?0.

0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=?
0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=?

0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y,当x=-1,y=2/3时,最后=?
先对原式化简,0.2X^2Y-0.5XY^2-0.3X^2Y+0.7X^2Y=(0.2-0.3+0.7)X^2Y-0.5XY^2=0.6X^2Y-0.5XY^2=XY(0.6X-0.5Y),然后将X,Y值带入.=(-1)×2/3×【0.6×(-1)-0.5×2/3】=2/3×14/15=28/45