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已知(x+1)2+|y-1|=0,求2(xy-5xy2)-(3xy2-xy)的值.
人气:108 ℃ 时间:2020-02-03 15:54:32
解答
2(xy-5xy2)-(3xy2-xy)
=(2xy-10xy2)-(3xy2-xy)
=2xy-10xy2-3xy2+xy
=(2xy+xy)+(-3xy2-10xy2
=3xy-13xy2
∵(x+1)2+|y-1|=0
∴(x+1)=0,y-1=0
∴x=-1,y=1.
∴当x=-1,y=1时,
3xy-13xy2=3×(-1)×1-13×(-1)×12
=-3+13
=10.
答:2(xy-5xy2)-(3xy2-xy)的值为10.
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