`(315-x)/101` + `(313-x)/103` + `(311-x)/105` + `(309-x)/107` =-4 Tìm `x`

12/09/2021

By Alice

`(315-x)/101` + `(313-x)/103` + `(311-x)/105` + `(309-x)/107` =-4
Tìm `x`

Đáp án:

`(315-x)/101+(313-x)/103+(311-x)/105+(309-x)/107=-4`

`=>(315-x)/101+(313-x)/103+(311-x)/105+(309-x)/107+4=0`

`=>((315-x)/101+1)+((313-x)/103+1)+((311-x)/105+1)+((309-x)/107+1)=0`

`=>((315-x)/101+101/101)+((313-x)/103+103/103)+((311-x)/105+105/105)+((309-x)/107+107/107)=0`

`=>(315-x+101)/101+(313-x+103)/103+(311-x+105)/105+(309-x+107)/107=0`

`=>(416-x)/101+(416-x)/103+(416-x)/105+(416-x)/107=0`

`=>(416-x)(1/101+1/103+1/105+1/107)=0`

`=>416-x=0` (vì `1/101+1/103+1/105+1/107\ne0`)

`=>x=416`

Vậy `x=416`