`2/3`-1`5/7`x=`-10/3` `1/10`:`(3/4-2x)^2`=0,4

`2/3 - 1 5/7 x = - 10/3`

`⇒ 1 5/7 x = 2/3 - ( - 10/3 )`

`⇒ 12/7 x = 4`

`⇒ x = 4 : 12/7`

`⇒ x = 7/3`

Vậy `, x = 7/3 .`

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`1/10 : ( 3/4 - 2x )^2 = 0,4`

`⇒ 1/10 : ( 3/4 - 2x )^2 = 2/5`

`⇒ ( 3/4 - 2x )^2 = 1/10 : 2/5`

`⇒ ( 3/4 - 2x )^2 = 1/4`

`⇒` \(\left[ \begin{array}{l}( \frac{3}{4} - 2x )^2 = ( \frac{1}{2} )^2\\( \frac{3}{4} - 2x )^2 = ( \frac{- 1}{2} )^2\end{array} \right.\) 

`⇒` \(\left[ \begin{array}{l}\frac{3}{4} - 2x = \frac{1}{2}\\\frac{3}{4} - 2x = \frac{- 1}{2}\end{array} \right.\) 

`⇒` \(\left[ \begin{array}{l}2x = \frac{1}{4}\\2x = \frac{5}{4}\end{array} \right.\) 

`⇒` \(\left[ \begin{array}{l}x = \frac{1}{8}\\x = \frac{5}{8}\end{array} \right.\) 

Vậy `, x ∈ { 1/8 ; 5/8 }`

Đáp án+Giải thích các bước giải:

 a,

`2/3-1 5/7x=-10/3`

`⇔2/3-12/7x=-10/3`

`⇔12/7x=2/3+10/3`

`⇔12/7x=4`

`⇔x=4: 12/7`

`⇔x=7/3`

Vậy `x=7/3`

b,

`1/10: (3/4-2x)^2=0,4`

`⇔(3/4-2x)^2=1/10: 2/5`

`⇔(3/4-2x)^2=1/4`

`⇔(3/4-2x)^2=(1/2)^2`

TH1:

`3/4-2x=1/2`

`⇔2x=3/4-2/4`

`⇔2x=1/4`

`⇔x=1/8`

TH2:

`3/4-2x=-1/2`

`⇔2x=3/4+2/4`

`⇔2x=5/4`

`⇔x=5/8`

Vậy `x={1/8,5/8}`