Question

The vertex of a parabola is (5, -3) and another point on the parabola is (1,5). Which point is also on the parabola?
A. (0, 3)
B. (-1, 9)
C. (-1, 15)
D. (7, 7)

Answer 1

Do you know of the vertex form of a parabola?

Answer 2

No

Answer 3

A parabola may be written in the form:
y = a(x - h)^2 + k
Where (h, k) is our vertex and a is some constant.

We can find a by substituting (5, -3) for (h,k) and (1, 5) in for (x,y) to solve a 1-variable equation.
Then we could go through each point listed and check whether it results in a true equation when plugged in for (x,y), keeping (5,-3) in for (h,k).

Answer 4

k imma write it out now

Answer 5

is it A (0,3)?

Answer 6

?

Answer 7

o.o
woah sorry, I didn't receive any updates on this question!
Just a moment!

Answer 8

I did not get A...
So you have:
y = a (x - h)^2 + k
(h,k) = (5,-3)
y = a (x - 5)^2 - 3
(x,y) = (1, 5)
5 = a(1 - 5)^2 - 3
8 = a (-4)^2 = 16a
a = 1/2
You got to this point?

Answer 9

We would sub this back in with the vertex:
y = 1/2 (x - 5)^2 - 3
We then plug (x,y) = (0,3). Notice the result:
3 = 1/2 (0 - 5)^2 - 3
3 = 25/2 - 3
3 = 12.5 - 3 = 9.5 That is not true!
So A is NOT correct.

Answer 10

how about c if thats not it im not sure

Answer 11

I got C as well.
You plug in x=-1
15 = 1/2 (-1 - 5)^2 - 3
15 = 1/2 * 6^ 2 - 3
15 = 36/2 - 3
15 = 18 - 3
15 = 15 is a true statement.

Answer 12

thank you @ Access Denied really appreciate it

Answer 13

Glad to be able to help. :)