What number should be added to both sides of the equation to complete the square?

x2 – 6x = 5

Completing the square is done as follows:

1. Write the equation in a way that the constants are in the right side while the terms with x are on the left. 
x^2 – 6x = 5

2. Make sure that the coefficient of the x^2 term is 1.
x^2 – 6x = 5

3. Adding a term to both sides that will complete the square in the left side. This is done by dividing the coefficient of the x term by 2 and squaring it. Note: The same amount should be added to the right side to balance the equation.
x^2 – 6x + 9 = 5 + 9

(x-3)^2 = 14

Therefore, 9 should be added to both sides to complete the square.