`text{Đáp án + Giải thích các bước giải}`
$a)$
`text{Ta có:}`
`7/8+x=3/5`
`⇔x=3/5-7/8`
`⇔x=-(11/40)`
Vậy `x=-11/40`
$b)$
`text{Ta có:}`
`1/2x-2/5=1/5`
`⇔1/2x=1/5+2/5`
`⇔1/2x=3/5`
`⇔x=3/5:1/2`
`⇔x=6/5`
Vậy `x=6/5`
`c)`
`|x+1|=2`
`⇔`\(\left[ \begin{array}{l}x+1=2\\x+1=-2\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2-1\\x=-2-1\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=1\\x=-3\end{array} \right.\)
Vậy `x=1` hoặc `x=-3`
$d)$`
`text{Ta có:}`
`(2-x).(4/5-x)=0`
`<=>`\(\left[ \begin{array}{l}2-x=0\\4/5-x=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2-0\\x=4/5-0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=2\\x=4/5\end{array} \right.\)
xin hay nhất.
