The first step of completing the square is to add the opposite of the constant term to both sides of an equation in standard form. But this has already been done for this problem, so proceed to the second step.
The second step is to divide through by the lead coefficient, but your lead coefficient is 1, so you don't have to do anything here either.
Step 3: Divide the first degree coefficient by 2, square the result, and add that result to both sides of your equation.
4 divided by 2 is 2. 2 squared is 4. Add 4 to both sides:
Step 4: Factor the perfect square trinomial (hence the name, "Completing The Square") in the LHS:
Step 5: Take the square root of both sides. Consider both positive and negative roots.
Step 6: Add the additive inverse of the constant on the left to both sides:
Done.
John
My calculator said it, I believe it, that settles it
