A student was given the equation x^2 + 6x - 13 = 0 to solve by completing the square. The first
step that was written is shown below.
x^2 + 6x = 13
The next step in the student’s process was x^2 + 6x + c = 13 + c.
State the value of c that creates a perfect square trinomial.
Explain how the value of c is determined.