已知:(x+2)2+|y+1|=0,求5xy2-2xy2-[3xy2-(4xy2-2x2y)]的值.
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已知:(x+2)2+|y+1|=0,求5xy2-2xy2-[3xy2-(4xy2-2x2y)]的值. |
答案
∵(x+2)2+|y+1|=0, ∴x+2=0,y+1=0, 解得x=-2,y=-1, ∵5xy2-2xy2-[3xy2-(4xy2-2x2y)], =5xy2-2xy2-[3xy2-(4xy2-2x2y)], =3xy2-3xy2+(4xy2-2x2y), =4xy2-2x2y, 当x=-2,y=-1时,原式=4xy2-2x2y, =4×(-2)×(-1)2-2×(-2)2(-1), =0. |
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