Đáp án + Giải thích các bước giải:
a)
`x-2/3=(-1)/2`
`=>x=(-1)/2+2/3`
`=>x=(-3)/6+4/6`
`=>x=1/6`
b)
`(-7)/2:(3-x)-0,75=1/4`
`=>(-7)/2:(3-x)-3/4=1/4`
`=>(-7)/2:(3-x)=1/4+3/4`
`=>(-7)/2:(3-x)=1`
`=>3-x=(-7)/2:1`
`=>3-x=(-7)/2`
`=>x=3-(-7)/2`
`=>x=6/2-(-7)/2`
`=>x=13/2`
c)
`20%x-x+1/5=3/4`
`=>1/5x-x+1/5=3/4`
`=>1/5x-x=3/4-1/5`
`=>1/5x-x=15/20-4/20`
`=>1/5x-x=11/20`
`=>x(1/5-1)=11/20`
`=>x(1/5-5/5)=11/20`
`=>x. (-4)/5=11/20`
`=>x=11/20:(-4)/5`
`=>x=11/20. 5/(-4)`
`=>x=11/4. 1/(-4)`
`=>x=11/(-16)`
`=>x=(-11)/16`
d)
`|2x-4/3|-1 1/3=(-8)/9`
`=>|2x-4/3|-4/3=(-8)/9`
`=>|2x-4/3|=(-8)/9+4/3`
`=>|2x-4/3|=(-8)/9+12/9`
`=>|2x-4/3|=(-8)/9+12/9`
`=>|2x-4/3|=4/9`
`=>`\(\left[ \begin{array}{l}2x-\frac{4}{3}=\frac{4}{9}\\2x-\frac{4}{3}=\frac{-4}{9}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}2x=\frac{4}{9}+\frac{4}{3}\\2x=\frac{-4}{9}+\frac{4}{3}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}2x=\frac{4}{9}+\frac{12}{9}\\2x=\frac{-4}{9}+\frac{12}{9}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}2x=\frac{16}{9}\\2x=\frac{8}{9}\end{array} \right.\)
`=>`\(\left[ \begin{array}{l}x=\frac{16}{9}:2\\x=\frac{8}{9}:2\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=\frac{16}{9}.\frac{1}{2}\\x=\frac{8}{9}.\frac{1}{2}\end{array}
\right.\)
`=>` \(\left[ \begin{array}{l}x=\frac{8}{9}.\frac{1}{1}\\x=\frac{4}{9}.\frac{1}{1}\end{array}
\right.\)
`=>` \(\left[ \begin{array}{l}x=\frac{8}{9}\\x=\frac{4}{9}\end{array}
\right.\)
Vậy `x∈{8/9;4/9}`
