ANSWER IT ONLY IF YOU KNOW THE ANSWER. IF YOU DONT KNOW DONT ANSWER IT. Make sure you explain please! Which of the following shows the correct first step to solve x^2 - 16x = -21 by completing the square?

A)x^2 - 16x + 64 = -21

B) x^2 - 16x + 64 = -21 + 64

C) x^2 - 16x + 16 = -21 + 16

D) x^2 - 16x + 8 = -21 + 8

I believe the answer would be B) x^2 - 16x + 64 = -21 + 64

Step-by-step explanation:

When you're completing the square you take the "middle" term (in this case it's -16) and you divide it by two, then square it. By doing that for this problem you get 64 (16/2 = 8 - 8^2 = 64; signs don't matter in this case because you multiply 2 negatives). You have to add that 64 to BOTH sides so that the equation evens out.

Ultimately, with it factored, the answer will be (x-8)^2

c is the correct answer

step-by-step explanation: