Bài 2: (2,0 điểm) Tìm x, biết: a) (-0,2) - x.$\frac{1}{6}$ = $\frac{2}{3}$ b) ($\frac{1}{3}$x - $\frac{8}{13}$).(2,5 + $\frac{-7}{5}$ : x) = 0 c) 5.($\frac{1}{\sqrt{25}}$ - x) - $\sqrt{\frac{1}{81}}$ = $\frac{-1}{9}$ d) |x| - $\frac{23}{17}$ = 0

Đáp án + Giải thích các bước giải:

`a)(-0,2)-x. 1/6=2/3`

`=>1/6x=-0,2-2/3`

`=>1/6x=-1/5-2/3`

`=>1/6x=-13/15`

`=>x=-13/15:1/6`

`=>x=-26/5`

Vậy `x=-26/5`

`b)(1/3x-8/13)(2,5+(-7)/5:x)=0`

`=>1/3x-8/13=0` hoặc `2,5-7/5:x=0`

`=>1/3x=0+8/13` hoặc `7/5:x=0+2,5`

`=>1/3x=8/13` hoặc `7/5:x=5/2`

`=>x=8/13:1/3` hoặc `x=7/5:5/2`

`=>x=24/13` hoặc `x=14/25`

Vậy `x in{24/13;14/25}`

`c)5.(1/\sqrt{25}-x)-\sqrt{1/81}=(-1)/9`

`=>5(1/5-x)-1/9=-1/9`

`=>5(1/5-x)=-1/9+1/9`

`=>5(1/5-x)=0`

`=>1/5-x=0`

`=>x=1/5`

Vậy `x=1/5`

`d)|x|-23/17=0`

`=>|x|=0+23/17`

`=>|x|=23/17`

`=>x=+-23/17`

Vậy `x in{23/17;-23/17}`