Đáp án:
$x =\pm\dfrac{81}{8}$
Giải thích các bước giải:
$1,25 -\dfrac{|x|}{3} + 2 = \left(-\dfrac12\right)^3$
$\Leftrightarrow \dfrac54 -\dfrac{|x|}{3} + 2 = -\dfrac18$
$\Leftrightarrow \dfrac{|x|}{3}=\dfrac54 + 2 +\dfrac18$
$\Leftrightarrow \dfrac{|x|}{3}=\dfrac{27}{8}$
$\Leftrightarrow |x| = \dfrac{81}{8}$
$\Leftrightarrow \left[\begin{array}{l}x =\dfrac{81}{8}\\x = -\dfrac{81}{8}\end{array}\right.$
