`g)` `|x+3/4|-|-5|=-|-2|`
`⇔|x+3/4|-5=-2`
`⇔|x+3/4|=3`
$⇔\left[ \begin{array}{l}x+\dfrac{3}{4}=3\\x+\dfrac{3}{4}=-3\end{array} \right.$
$⇔\left[ \begin{array}{l}x=-\dfrac{9}{4}\\x=-\dfrac{15}{4}\end{array} \right.$
Vậy `x=-9/4` hoặc `x=-15/4`.
`b)` `(3x+2)^3=-27`
`⇔(3x+2)^3=(-3)^3`
`⇔3x+2=3`
`⇔3x=1`
`⇔x=1/3`
`c)` `(2x-5)^20+(2y+3)^50=0`
Ta có: `(2x-5)^20≥0` với mọi `x`
`(2y+3)^50≥0` với mọi `y`
Mà `(2x-5)^20+(2y+3)^50=0`
⇒$\left \{ {{2x-5=0} \atop {2y+3=0}} \right.$
⇒$\left \{ {{x=\frac{5}{2}} \atop {y=-\frac{3}{2}}} \right.$
Vậy `x=5/2` và `y=-3/2`.
`d)` `|1/2 x - 1| (x+1) = 2|1/2 x -1|`
`⇒x+1 = 2| 1/2 x -1| : | 1/2 x - 1|`
`⇒x+1=2`
`⇒x=1`
`e)` `|x| - (-2)^2 = sqrt 9`
`⇒|x|-4=3`
`⇒|x|=7`
`⇒x=7` hoặc `x=-7`
Vậy `x=7` hoặc `x=-7`.
`g)` `4 1/3 : x= 6 : 0,3`
`⇒13/3 : x=20`
`⇒x=13/60`
Vậy `x=13/60`
