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?
a. subtraction property of equality
b. completing the square
c. factoring out the constant
d. zero property of multiplication

Option a is correct

Subtraction property of equality

Step-by-step explanation:

Given the quadratic equation:

         .....[1]

Subtraction property of equality states that you subtract the same number to both sides of an equation.

Subtract c from both sides in [1] we have;

Simplify:

Therefore, the step 1 justifies the subtraction property of equality

b.-4 units

all you   do is count how many times you move

answer: apothems is your answer

step-by-step explanation: hope u get it right