The first step for deriving the quadratic formula from the quadratic equation, 0 = ax2 + bx + c, is shown.
Step 1: –c = ax2 + bx
Which best explains or justifies Step 1?
subtraction property of equality
completing the square
factoring out the constant
zero property of multiplication
1 answer
The completion of the square justifies Step 1. By subtracting c from both sides of the equation, we are isolating the terms involving x on the left side, which is a necessary step in completing the square to ultimately derive the quadratic formula.