How can you use the quadratic formula to complete a square?

It has become somewhat fashionable to have students derive the Quadratic Formula themselves; this is done by completing the square for the generic quadratic equation ax2 + bx + c = 0. While I can understand the impulse (showing students how the Formula was invented, and thereby providing a concrete example of the usefulness of abstract symbolic manipulation), the computations involved are often a bit beyond the average student at this point.

Step 1 Divide all terms by a (the coefficient of x2).Step 2 Move the number term (c/a) to the right side of the equation.Step 3 Complete the square on the left side of the equation and balance this by adding the same value to the right side of the equation.