Đáp án`+`Giải thích các bước giải:

 `e, (3/4 - 7x)^2 = 1/4`

`=>` $\left[\begin{matrix} \dfrac{3}{4} - 7x = \dfrac{1}{2}\\ \dfrac{3}{4} - 7x = \dfrac{-1}{2}\end{matrix}\right.$

`=>` $\left[\begin{matrix} 7x = \dfrac{1}{4}\\ 7x = \dfrac{5}{4}\end{matrix}\right.$

`=>` $\left[\begin{matrix} x = \dfrac{1}{28}\\ x =\dfrac{5}{28}\end{matrix}\right.$

Vậy `x \in {1/(28);5/(28)}`

`g, (2/5 - 3x)^2 - 1/5=  4/(25)`

`=> (2/5 - 3x)^2 = 9/(25)`

`=>` $\left[\begin{matrix} \dfrac{2}{5} - 3x = \dfrac{3}{5}\\ \dfrac{2}{5} - 3x= \dfrac{-3}{5}\end{matrix}\right.$

`=>` $\left[\begin{matrix} 3x= \dfrac{-1}{5}\\ 3x= 1\end{matrix}\right.$

`=>` $\left[\begin{matrix} x=\dfrac{-1}{15}\\ x=\dfrac{1}{3}\end{matrix}\right.$

Vậy `x \in {-1/(15);1/3}`

`***`sharksosad