`(3*x+2)^2=121`
\(=>\left[{}\begin{matrix}3x+2=11\\3x+2=-11\end{matrix}\right.\\ =>\left[{}\begin{matrix}3x=11-2\\3x=-11-2\end{matrix}\right.\\ =>\left[{}\begin{matrix}3x=9\\3x=-13\end{matrix}\right.\\ =>\left[{}\begin{matrix}x=3\left(tm\right)\\x=-\dfrac{13}{3}\left(loại\right)\end{matrix}\right.\)
`(3x+2)^2=121`
`=>( 3x+2)^2= +-11^2`
\(\Rightarrow\left[{}\begin{matrix}3x+2=11\\3x+2=-11\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}3x=9\\3x=-13\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{13}{3}\end{matrix}\right.\)