Question

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

Answer 1

Subtraction property of equality — you subtract c from both sides of 0 = ax^2 + bx + c to get -c = ax^2 + bx (same operation on both sides preserves equality).