Question

当x/1-y/1＝3,求x-2xy-y/2x+3xy-2y的值.

Answer 1

1/x-1/y=3
等式两边同时乘以xy
y-x=3xy
等式两边同时乘以-1
x-y=-3xy
(2x+3xy-2y)/(x-2xy-y)
=[2(x-y)+3xy]/[(x-y)-2xy]
=(-6xy+3xy)/(-3xy-2xy)
=(-3xy)/(-5xy)
=3/5
答案是正确的哟!
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