Đáp án + Giải thích các bước giải:
`a,3/4+1/4÷x=-2`
`=>1/4÷x=-2-3/4`
`=>1/4÷x=-11/4`
`=>1/4÷(-11/4)=x`
`=>x=-1/11`
Vậy `x=-1/11`
`b,|3x-5|-|-3/2|=5`
`=>|3x-5|-3/2=5`
`=>|3x-5|=5+3/2`
`=>|3x-5|=13/2`
\(⇒\left[ \begin{array}{l}3x-5=\dfrac{13}2\\3x-5=-\dfrac{13}2\end{array} \right.\)
\(⇒\left[ \begin{array}{l}3x=\dfrac{23}2\\3x=-\dfrac{3}2\end{array} \right.\)
\(⇒\left[ \begin{array}{l}x=\dfrac{23}6\\x=-\dfrac{1}2\end{array} \right.\)
Vậy `x={23/6;-1/2}`
`c,[x-1]/4=[-9]/[1-x]`
`=>[x-1]/4=[-9]/[-(x-1)]`
`=>[x-1]/4=[9]/[x-1]`
`=>(x-1)^2=4.9`
`=>(x-1)^2=36`
\(⇒\left[ \begin{array}{l}x-1=6\\x-1=-6\end{array} \right.\)
\(⇒\left[ \begin{array}{l}x=7\\x=-5\end{array} \right.\)
Vậy `x={7;-5}`
