`1) | x - 3 | + | -2 | = | -5 |`
`| x - 3 | + 2 = 5`
`| x - 3 | = 5 - 2`
`| x - 3 | = 3`
\(\left[ \begin{array}{l}x-3=3\\x-3=-3\end{array} \right.\)
\(\left[ \begin{array}{l}x=3+3\\x=-3+3\end{array} \right.\)
\(\left[ \begin{array}{l}x=6\\x=0\end{array} \right.\)
`\text{Vậy} x ∈ { 0 ; 6 }`
`2) | 1/4 - x | + 2/3 = 1/2`
`| 1/4 - x | = 1/2 - 2/3`
`| 1/4 - x | = 3/6 - 4/6`
`| 1/4 - x | = -1/6`
`\text{mà} | 1/4 - x | ≥ 0 ∀x \text{( với mọi x )}`
`-1/6 < 0`
`=> | 1/4 - x | \ne -1/6`
`=> x ∈ ∅`
`3) | x - 3/7 | + | y + 1/5 | = 0`
`=> {( | x - 3/7 | = 0 ) , ( | y + 1/5 | = 0 ):}`
`{( x - 3/7 = 0 ) , ( y + 1/5 = 0 ):}`
`{( x = 3/7 ) , ( y = - 1/5 ):}`
`\text{Vậy} x = 3/7 ; y = -1/5`