Giải thích các bước giải:
$a)(x+1)^2=15$
$⇔(x+1)^2=(±\sqrt{15})^2$
$⇔x+1=±\sqrt{15}$
$⇔$ \(\left[ \begin{array}{l}x+1=\sqrt{15}\\x+1=-\sqrt{15}\end{array} \right.\) $⇔$ \(\left[ \begin{array}{l}x=\sqrt{15}-1 \\x=-\sqrt{15}-1\end{array} \right.\)
$\text{Vậy $x∈\{-\sqrt{15}-1;\sqrt{15}-1\}$}$
$\text{Nếu sai đề:}$
$(x+1)^2=16$
$⇔(x+1)^2=(±4)^2$
$⇔x+1=±4$
$⇔$ \(\left[ \begin{array}{l}x+1=4\\x+1=-4\end{array} \right.\) $⇔$ \(\left[ \begin{array}{l}x=3 \\x=-5\end{array} \right.\)
$\text{Vậy $x∈\{-5;3\}$}$
$b)2^{x+1}=16$
$⇔2^{x+1}=2^4$
$⇔x+1=4$
$⇔x=3$
$\text{Vậy $x=3$}$
Học tốt!!!
