we have that
x²+ 12x = -5
Group terms that contain the same variable, and move the constant to the opposite side of the equation(x²+ 12x) = -5
Complete the square. Remember to balance the equation by adding the same constants to each side
(x²+ 12x+36) = -5+36
Rewrite as perfect squares(x+6)² = -5+36
the answer is36