先化简,再求值:2(x눀y+xy)-3(x눀y-xy)-4x눀y,期中x=-1,y=1⼀3

2025-05-17 12:19:04
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回答1:

=2x²y+2xy-3x²y+3xy-4x²y
=-5x²y+5xy

x=-1,y=1/3
原式=-5x(-1)²x 1/3 +5x(-1)x 1/3=-10/3

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