# Can anyone teach me how to solve a Quadratic equation by completing the square? Thanks..

##### 1 Answer

The idea behind completing the square is to add or subtract a constant to obtain the form

Starting from

Step 1: Divide both sides by

Step 2: Add

Step 3: Add a constant to both sides which will allow us to factor the left hand side as

Step 4: Factor the left hand side

Step 5: Take the square root of both sides. Remember to account for both positive and negative roots.

Step 6: Solve the remaining linear equation:

The real trick here is observing in step 3 that the constant we need to add is equal to the square of half of the coefficient of

Let's see what happens if we apply this to a general quadratic equation.

And we have just derived the quadratic formula.