x y电影经典语录

x y电影经典语录

7x-2y=0, 即x/y=2/7 y/x=7/2 [(x/y)-(y/x)]/[(x/y)-1+(y/x)] =[(2/7)-(7/2)]/[(2/7)-1+(7/2)] =[(4-49)/14]/[(4+49-14)/14] =-15/13

7x-2y=0 x=2y/7 [(x/y)-(y/x)]/[(x/y)-1+(y/x)] =[(2y/7)/y-(y/(2y/7))]/[(2y/7)/y-1+(y/(2y/7))] =(2/7-7/2)/(2/7-1+7/2)=-15/13

解：由已知可得x、y都不等于0，又由7x-2y=0，可设x=2t,y=7t(t不等于0),则 [(x/y)-(y/x)]/[(x/y)-1+(y/x)]=(2/7-7/2)/(2/7-1+7/2) =(4-49)/(4-14+49)=-15/13.

∵7x-2y=0 ∴x/y=2/7 ∴[(x/y)-(y/x)]/[(x/y)-1+(y/x)]=(2/7-7/2)/(2/7-1+7/2)=-49/39

同上

解： 因为7x-2y=0所以 x/y=2/7,y/x=7/2 [(x/y)-(y/x)]/[(x/y)-1+(y/x)]=[2/7-7/2]/[2/7-1+7/2]=-45/39=-15/13

前人之述备矣

https://www.zhihu.com/question/47126105