Question

I need to find the vertex of the parabola y=9x^2+7 but I am confused on what to use for b. I know a=9 but am unsure if b=7. Does b=7?

Answer 1

since there is no x term, b=0

y = 9x^2 + 0x + 7

Answer 2

9 x^2 + 0 x + 7 = y

Well, first sketch a graph of this parabola.
Note that it is symmetric about the y axis. In other worda it is the same fo x = -537 and x = + 537 or whatever number because x^2 = (-x)^2 and there is no b x term.
so the vertex is where x = 0
then y = 7
so (0,7)

now do it right
9 x^2 = y-7
x^2 = (y-7)/9
(x-0)^2 = (1/9)(y-7)
so
vertex at (0 , 7) as we knew

Answer 3

So if I put 0 in a b I would get 0/18 which equals 0 for x?

Answer 4

Hmmm, I am not sure what 18 has to do with the affair.

Answer 5

I'm using the formula -b/2a for the function9x^2+7. So I would get -0/2(9) which equals -0/18 and the final result is 0.

Answer 6

Oh, ok, anyway zero is the right answer.

Answer 7

That is just fine. I completed the square because I am a creature of habit.

Answer 8

Thanks