已知1/x-1/2y=1/3求代数式2x+3y-4y/x-3y-2y的值
问题描述：
已知1/x-1/2y=1/3求代数式2x+3y-4y/x-3y-2y的值
答
(2x+3xy-4y)/(x-3xy-2y)
=(2/y+3-4/x)/(1/y-3-2/x)
=[3-4(1/x-1/2y)]/[-3-2(1/x-1/2y)]
=(3-4/3)/(-3-2/3)
=(9-4)/(-9-2)
=5/11