Question

Here are two steps from the derivation of the quadratic formula (image w question below)

Answer 1

B. Completing the square

Explanation:

Between the first and second steps shown, the square of half the x-term coefficient was added to both sides. That is a value that makes the polynomial on the left be a "perfect square trinomial."

The process of adding the value required to make the left side a perfect square is called "completing the square."