Đáp án:
Giải thích các bước giải:
Bài 8 :
a)
$(2x-1)^{4}$ = $16$
$⇒$ $(2x-1)^{4}$ = $2^{4}$ hoặc $(-2)^{4}$
$⇒$ \(\left[ \begin{array}{l} 2x-1=2\\2x-1=-2\end{array} \right.\) $⇒$ \(\left[ \begin{array}{l}2x=2+1\\2x=-2+1\end{array} \right.\) $⇒$ \(\left[ \begin{array}{l}x=\dfrac{3}{2}\\x=\dfrac{-1}{2}\end{array} \right.\)
c)
$||x+3|-8|=20$
$⇒$ \(\left[ \begin{array}{l}|x+3|-8|=20\\|x+3|-8|=-20\end{array} \right.\)
$⇒$ \(\left[ \begin{array}{l}|x+3|=28\\|x+3|=-12(vô lý-loại) \end{array} \right.\)
$⇒$ \(\left[ \begin{array}{l}x+3=28\\x+3=-28\end{array} \right.\) $⇒$ \(\left[ \begin{array}{l}x=25\\x=-31\end{array} \right.\)
