$a, ( x + \dfrac{3}{4} ) ² = \dfrac{4}{25}$
$ ( x+ \dfrac{3}{4})²$ = $\frac{2²}{5²}$
$ x + \dfrac{3}{4}$ = $±\dfrac{2}{5}$
TH1:
$ x + \dfrac{3}{4}$ = $\dfrac{2}{5}$
$x = \dfrac{2}{5}$ - $\dfrac{3}{4}$
$x =\dfrac{-7}{20} $
TH2:
$ x + \dfrac{3}{4} = -\dfrac{2}{5}$
$x =-\dfrac{2}{5} -\dfrac{3}{4}$
$x =\dfrac{-23}{20} $
$b, ( \dfrac{4}{7} - \dfrac{1}{2}x ) ³ = 8$
$( \dfrac{4}{7} -\dfrac{1}{2}x ) ³ = 2³$
$\dfrac{4}{7} -\dfrac{1}{2}x = 2$
$ -\dfrac{1}{2}x $= 2- $\dfrac{4}{7} $
$ -\dfrac{1}{2}x$ = $\dfrac{10}{7} $
$x = \dfrac{10}{7} $ : $\dfrac{-1}{2} $
$x = \dfrac{20}{7}$
$c, x³ = -8$
$x³ = -2³$
$x = -2$
$D, 9^{x-1} =\dfrac{1}{9} $
$9^{x-1} =9^{-1}$
$x - 1 = -1 $
$x = -1 +1 $
$x = 0 $
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