Answer
The solutions are $x=1$ and $x= -7$.
Work Step by Step
The given equation is
$\Rightarrow x^2+6x+9=16$
The coefficient of the $x^2-$term is $1$, and the coefficient of the $x-$term is an even number.
So, solve by completing the square.
Write the left side as the square of a binomial.
$\Rightarrow (x+3)^2=16$
Take the square root of each side.
$\Rightarrow x+3=\pm\sqrt{16}$
Subtract $3$ from each side.
$\Rightarrow x+3-3=-3\pm\sqrt{16}$
Simplify.
$\Rightarrow x=-3\pm4$
The solutions are $x=-3+4=1$ and $x=-3-4= -7$.
