\(\Leftrightarrow\left(3x+5\right)^2=3^2=\left(-3\right)^2\\ \Leftrightarrow\left[{}\begin{matrix}3x+5=3\\3x+5=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}3x=-2\\3x=-8\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{2}{3}\\x=-\dfrac{8}{3}\end{matrix}\right.\)
(3x + 5)2 = 9
(3x + 5)2 = 32
3x + 5 = 3
3x = 3 - 5
3x = -2
x = -2 : 3
X = \(\dfrac{-2}{3}\)