x/3=y/4,求(xx-xy)/(xx+y*y)的值

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x/3=y/4,求(x*x-xy)/(x*x+y*y)的值
x/3=y/4,求(x*x-xy)/(x*x+y*y)的值

x/3=y/4,求(x*x-xy)/(x*x+y*y)的值
令x/3=y/4=k
x=3k,y=4k
(x^2-xy)/(x^2+y^2)
=(9k^2-12k^2)/(9k^2-16k^2)
=-3k^2/(-7k^2)
=3/7

楼上的.你符号都错了.......
设比例中一份为K
原式=(9k方-12K方)/(9K方+16K方)
=-3/25
此为正确答案

3/25为正确答案。

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