How do you use the completing the square method to solve a quadratic equation?

First you need to get the quadratic equation in completed square form. 
This looks like: (x+p)^2 + q 

To put an expression in completed square form you can use this formula: x^2 + 2bx + c = (x+b)^2 - b^2 + c

Once in this form you can solve the equation for x by rearranging. 

For example: solve x^2 + 4x -5=0 using the completing the square method.

Using the formula with b = 2 and c = -5 gives: (x+2)^2 – 2^2 – 5 = 0

And simplifying leads to:

(x+2)^2 – 9 = 0 Rearranging gives:

(x+2)^2 = 9

x + 2 = ± 3

x = - 2 ± 3 

So the answers are:

x = 1 or x= -5