a) $(x-5)^2=36=6^2$
$x-5=6$
$⇒x=6+5=11$
b) $x^2=121x$
$x^2-121x=0$
$x.(x-121)=0$
\(⇒\left[ \begin{array}{l}x=0\\x-121=0\end{array} \right.\)
\(⇒\left[ \begin{array}{l}x=0\\x=121\end{array} \right.\)
c) $x^3=64x$
$x^3-64x=0$
$x(x^2-64)=0$
\(⇒\left[ \begin{array}{l}x=0\\x^2-64=0\end{array} \right.\)
\(⇒\left[ \begin{array}{l}x=0\\x^2=64\end{array} \right.\)
\(⇒\left[ \begin{array}{l}x=0\\x=8,-8\end{array} \right.\)
d) $x^3=1$
$⇒x=1$
e) $x^3=-1$
$⇒x=-1$
