来自丁钢的问题
已知(3a-b)/(2b-a)=7,(x+y)/(2x-y)=5,求(ax-2by)/(ax+2by)的值.
已知(3a-b)/(2b-a)=7,(x+y)/(2x-y)=5,求(ax-2by)/(ax+2by)的值.
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2020-12-28 11:32
已知(3a-b)/(2b-a)=7,(x+y)/(2x-y)=5,求(ax-2by)/(ax+2by)的值.
已知(3a-b)/(2b-a)=7,(x+y)/(2x-y)=5,求(ax-2by)/(ax+2by)的值.
(3a-b)/(2b-a)=7
3a-b=14b-7a
10a=15b
a=3b/2
(x+y)/(2x-y)=5
x+y=10x-5y
9x=6y
∴x=2y/3
∴ax=3b/2×2y/3=by
∴(ax-2by)/(ax+2by)
=(by-2by)/(by+2by)
=-1/3