若7x-2y=0,則[(x/y)-(y/x)]/[(x/y)-1+(y/x)]=?

熱心網(wǎng)友

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

熱心網(wǎng)友

同上

熱心網(wǎng)友

7x-2y=0x=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

熱心網(wǎng)友

解：因?yàn)?x-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

熱心網(wǎng)友

解：由已知可得x、y都不等于0，又由7x-2y=0，可設(shè)x=2t,y=7t(t不等于0),則[(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.

熱心網(wǎng)友

∵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