`d2)|2x+6|-x=3`
`⇔|2x+6|=3+x`
`⇔`\(\left[ \begin{array}{l}2x+6=3+x;(ĐK:x≥-3)\\2x+6=-(3+x);(ĐK:x<-3)\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}2x-x=3-6\\2x+x=(-3)-6\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-3(TM)\\x=-3(KTM)\end{array} \right.\)
Vậy: `S=-3`
`d3)|x-3|+3x=5`
`⇔|x-3|=5-3x`
`⇔`\(\left[ \begin{array}{l}x-3=5-3x;(ĐK:x≥3)\\x-3=-(5-3x);(ĐK:x<3)\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x+3x=5+3\\x-3x=(-5)+3\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=2(KTM)\\x=1(TM)\end{array} \right.\)
Vậy: `S=1`
Xin hay nhất,tuy rằng ko thể xin đc =="
