Question

Write a quadratic function that fits the given set of points.

(2, 3), (6, 3), and (8, -3)

Answer 1

I have some already, let me type it!

Answer 2

3 = 4a + 2b + c
3 = 36a + 6b + c
-3 = 64a + 8b + c


I have done the work up until that point because I am confused.

Answer 3

Hello, Ric! Good evening. I especially appreciate it when you've done some work already and can share it.
Put into your own words what your goal is from this point forward.

Answer 4

I need to write a quadratic equation that coincides with the set of points that I had sown.
So far I have that much, I have to solve for a, b, and c. After that is that I need to write the function.

Answer 5

What you've got so far is exactly right.

Answer 6

Cool. Right on target!

What you have shared here is a system of linear equations.
What tools have you used in the past to solve such systems?
I can think of half a dozen right off, but want to know what y ou're familiar with.

Answer 7

Do you have any rough notion of what the quadratic function that fits these points will be?

Answer 8

So far I have just implanted the y and x into the quadratic function f(x)=ax^2+bx+c

Answer 9

is it a circle, a hyperbola, parabola, ellipse, etc? not essential to know off the top of your head...

Answer 10

Yes; that's how you came up with this system of linear equations.
But I'm asking you now to consider how you would solve this system of linear equations for a, b and c.

Answer 11

I've already solved the system using matrices on my TI-83 calculator. But there are several other ways of doing that. Which are reasonably familiar to you?

Answer 12

Isn't it a parabola?

Answer 13

Yes, it is a parabola.

Answer 14

Quadratic functions do have parabolic graphs.

Answer 15

you can deduce that the parabola must open downward, because we have two points with the same y value (2, 3) and (6,3) and a 3rd point which has a lower y value (8,-3). that means that the value of a must be negative.

Answer 16

whp: What tips could we provide Ric that will help him solve that system of linear equations?

Answer 17

sorry, because the 3rd point is not between those two points with the same y value, you can make that conclusion. not if between them!

Answer 18

I wish I had a graphing calculator. I could never find one. But so far I just d it like this:

Answer 19

have you done elimination to solve systems of 3 variables?

Answer 20

I don't know what that is @whpalmer4

Answer 21

@mathmale I need to make dinner, can you teach him how to do it?

Answer 22

RIC, I've looked at y our work (thanks for sharing the image) and see that you've tried subtraction as a means of eliminating one variable, so that you can solve for the other variable. Right on. It's just that some of the math isn't correct.

Would you rather focus on your example, in this image, or on the system of linear equations that you need to solve to answer this question.

Answer 23

I would rather do the one that I need to solve. An also, I have a question for you @mathmale

Answer 24

Go right ahead with your question first.

Answer 25

I am an online student, I am sick of it. I want to go to public school so that I can have someone teach me my subjects instead of me teaching myself. I have 5 assignments left until I finish the class. I have already gone into the assignments and done what I know I can do on my own, but there are some things that are confusing to me that they don't really touch well in my lessons. If it is okay with you, Would you mind helping me finish my class. There are a couple of the assignments that are mostly graph work (like making graphs, making lines, graphing points, etc.) But would you be willing to help me finish, When you help me on this website, you are so helpful. Would you help me finish my class?


I would have sent this in a private message but for some reason, the message system is not functioning properly.

Answer 26

I'll try to respond by private message right now.

Answer 27

Let me know if and when you've received my private message.

Answer 28

I received it!

Answer 29

Good. I'll wait for your response before we move on. You set the direction.

Answer 30

It still will not let me send anything.
Usually the "Submit" tab is blue and turns grey when it sends. In order to go to public school, I must be enrolled before tuesday so that they can get me into the classes I need. So that gives me all I can get done tonight and in the morning tomorrow. I don't have to take any exams or anything like that because they split it up into 4 tests throughout the course, which I did rather well on. But I really need to finish by tomorrow, which I know shouldn't take too long. after all, it is only 3 assignments that I might need help with. I only have 5

Answer 31

In that case we'd better get started right away! I'll be away tomorrow, but we'd still have a couple of hours. Important that you set your priorities so that we focus on whatever will do you the most good.

Answer 32

I am in Southern California and so am 3 hours behind you. Normally I get up at around 6, which would be 9 a.m. tomorrow morning your time.

Answer 33

Oh okay! Yes, I live on Florida. I usually stay up doing school so I am kind of used to the late nights/early mornings. What time is it over there right now?

Answer 34

7:41 p.m. I'll be hitting the sack by around 9:30; at least, I'd like to. Let's get started on the math that you most need to know and understand.

Answer 35

And before we continue with our working/conversation, I would like to open a new question so that Mr. whpalmer4 doesn't keep getting notifications