Question

I need help solving the rest of this problem.

Suppose a parabola has vertex (-4, 7) and also passes through the point (-3, 8). Write the equation of the parabola in vertex form.

Answer 1

This is what I have so far. I plugged in the vertex and the point it passes through.

y = a(x - h)^2 + K

8 = a(-3 - 4)^2 + 7

8 = a(-7)^2 + 7

After this I am not sure what to do. I think you subtract 7 from both sides but I am not sure. Any help is appreciated.

Answer 2

I have done that. Now I am trying to solve for a so I can then plug it back into the original equation.

Answer 3

You should be able to plug in the x & y coordinates that the parabola passes through (not the vertex), then you'll be able to solve for a

Answer 4

1. Replace h with -4, k with 7, x with -3, y with 8.
2. Solve that equation for a
3. Rewrite the equation replacing h with -4, k with 7, and a with the value from step 2
4. Walla!!! You are done.

Answer 5

"walla" lol
is it that you're confused how to solve for a once you've plugged in all your values?

Answer 6

Ok, I plugged in all the values. 8 = a(-3 - 4)^2 + 7.

8 = a(-7)^2 + 7, what do I do after this? Do I subtract 7 from both sides?

Answer 7

Yesss

Answer 8

Okay, so after I subtract 7 from both sides I am left with 1 = a(-7)^2. What do I do after this. This is where I got stuck.

Answer 9

What's 7^2?
Divide both sides by that number :)

Answer 10

sorry, 7^2 and (-7)^2 equal the same thing

Answer 11

They were just lost on the order of operations, not how to do the problem in general :)

Answer 12

I know how to write the equation out with the points I am given. I typed the equation out in my first post.

Answer 13

Did you get the solution for a though?

Answer 14

I am working on it, give me a sec.

Answer 15

Oh alright lol

Answer 16

The post directly under that showed me what I already know. A lot of people were posting and if I missed a post by you, that doesn't give you the right to be a douche. I am not good at math and insulting people on here is not how you go about things.

Answer 17

^ lol you're doing well, don't worry. :)

Answer 18

a = 1 right?

Answer 19

Waittt, lemme show you
So you had 1=a(-7)^2
So first (-7)^2 = 49
So, 1 = 49a
Divide both sides by 49 and you've got your answer :)

Answer 20

I had written the equation wrong. So the equation should've looked like 8 = a(-3 + 4)^2 +7.

8 = a(1)^2 + 7

Subtract 7 from each side and it becomes

1 = a(1)^2

Answer 21

OH then yeah you're right! Sorry lol

Answer 22

It's ok, thanks for both of your guys' help. I appreciate it.

Answer 23

No prob, lemme know if you need more help :)

Answer 24

Will do!