$\huge\text{|}$`|x-5| - x$\huge\text{|}$`=4`
`⇔` `|x-5|-x = 4 ` hoặc `|x-5|-x=-4`
TH1 : Nếu `x≥5` ta có :
`x-5-x=4` hoặc `x-5-x=-4`
`⇔ x-x = 4+5` `⇔ x-x=-4+5`
`⇔ 0x = 9` `(KTM)` `⇔ 0x = 1` `(KTM)`
TH2: Nếu `x<5` ta có :
`-(x-5)-x=4` hoặc `-(x-5)-x=-4`
`⇔ -x+5-x=4` `⇔ -x+5-x=-4`
`⇔ -x-x=4-5` `⇔ -x-x= -4-5`
`⇔ -2x=-1` `⇔ -2x=-9`
`⇔ x=1/2` `(TM)` `⇔ x=9/2` `(TM)`
Vậy `x=1/2` hoặc `x=9/2`
Học tốt !
