Tìm x a, (2x - 3)² = 16 b, ( -1/3)³ . x = 1/81

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Trả lời:

$a, (2x-3)^2=16$

\(⇔\left[ \begin{array}{l}2x-3=4\\2x-3=-4\end{array} \right.\)\(⇔\left[ \begin{array}{l}x=\dfrac{7}{2}\\x=-\dfrac{1}{2}\end{array} \right.\)

 Vậy $S=\{\dfrac{7}{2};-\dfrac{1}{2}\}$

$b, \bigg{(}-\dfrac{1}{3}\bigg{)}^3.x=\dfrac{1}{81}$

$⇔-\dfrac{1}{27}.x=\dfrac{1}{81}$

$⇔x=-\dfrac{1}{3}$

Vậy $S=\{-\dfrac{1}{3}\}$.