Đáp án:
`a, ptvn`
`b,` \(\left[ \begin{array}{l}x=-\frac{1}{30}\\x=-\frac{11}{30}\end{array} \right.\)
`c,` \(\left[ \begin{array}{l}x=3\frac{1}{4}\\x=\frac{11}{4}\end{array} \right.\)
`d,` \(\left[ \begin{array}{l}x=-10,75\\x=15,75\end{array} \right.\)
`e,` \(\left[ \begin{array}{l}x=\frac{4}{3}\\x=-\frac{28}{15}\end{array} \right.\)
Giải thích các bước giải:
`a,`
`3/4 - |2x+1|=7/8`
`=> |2x+1|=-1/8`
`|2x+1| >= 0 ∀x` mà `-1/8 <0`
`=>x ∈ ∅`
`=> ptvn`
`b,`
`1/2 - |x+1/5| = 1/3`
`=> |x+1/5|=1/6`
`=>`\(\left[ \begin{array}{l}x+\frac{1}{5}=\frac{1}{6}\\x+\frac{1}{5}=-\frac{1}{6}\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-\frac{1}{30}\\x=-\frac{11}{30}\end{array} \right.\)
`c,`
`2.|x-3|=1/2`
`=> |x-3|=1/4`
`=>` \(\left[ \begin{array}{l}x-3=\frac{1}{4}\\x-3=-\frac{1}{4}\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=3\frac{1}{4}\\x=\frac{11}{4}\end{array} \right.\)
`d,`
`75-3|5-2x|=-4,5`
`=> |5-2x|=26,5`
`=>` \(\left[ \begin{array}{l}5-2x=26,5\\5-2x=-26,5\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-10,75\\x=15,75\end{array} \right.\)
`e,`
`|x+4/15| - |-3,75|=-|-2,15|`
`=> |x+4/15 | = -2,15 + 3,75`
`=> |x + 4/15|=1,6`
`=>` \(\left[ \begin{array}{l}x+\frac{4}{15}=1,6\\x+\frac{4}{15}=-1,6\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=\frac{4}{3}\\x=-\frac{28}{15}\end{array} \right.\)
