先化简,再求值:5xy2-2x2y+[3xy2-(4xy2-2x2y)],其中x=-2,y=-1

先化简,再求值:5xy2-2x2y+[3xy2-(4xy2-2x2y)],其中x=-2,y=-1.
2025-05-14 18:03:04
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回答1:

5xy2-2x2y+[3xy2-(4xy2-2x2y)],
=5xy2-2x2y+3xy2-4xy2+2x2y,
=4xy2
当x=-2,y=-1时,代入上式得:
原式=4×(-2)×(-1)2
=-8