The first step for deriving the quadratic formula from the quadratic equation, 0 = ax^2 + bx + c, is shown.
step 1: –c = ax^2 + bx
which best explains or justifies step 1?
1)subtraction property of equality
2)completing the square
3)factoring out the constant
3)zero property of multiplication

1) Subtraction property of equality

Step-by-step explanation:

Subtraction property of equality states that an equation does not change by subtracting a same number from both sides of the equation.

In completing the square method, we convert a quadratic function to a perfect square trinomial,

In factoring out the constant, we split the middle term (term having degree 1) of a quadratic equation by factoring the constant,

Zero property of multiplication states that if the product of two numbers is zero then either of the number or expression must be zero or both are zero.

Here, the given equation,

By subtraction property of equality,

Hence, OPTION 1) would be correct.

she played for 18.75 hours.

step-by-step explanation:

if she played 2/4 of a hour on tuesday. and there is 60 minutes in an hour and 60 divided by 4 is 7.5. and she played 2/4 of an hour on thursday then again 60 divided by 4 is 7.5, you add 7.5+7.5=56.25. now you have to do 1/4 of an hour, it equals 3.75. now you have to add them all up. 3.75+7.5+7.5=18.75

i hope this and i hope you get it right. it took me a while to get this done for you. : )

55? i think maybe

step-by-step explanation: