# Math Help - How do you find a quadratic function?

1. ## How do you find a quadratic function?

Plot the points (scatter plot?)

Find quadratic function that best models:
(-4,37)
(-3,19)
(-2,7)
(-1,1)
(0,1)
(1,7)
(2,19)

Do I use my calculator? If so, how?

2. Originally Posted by kcwillia377
Plot the points (scatter plot?)

Find quadratic function that best models:
(-4,37)
(-3,19)
(-2,7)
(-1,1)
(0,1)
(1,7)
(2,19)

Do I use my calculator? If so, how?
As you have the point (0,1) you know it will be $y = ax^2+bx+1
$

Now you can do $1 = a -b$, $a = 1+b$ and $7 = a + b$

7 = (1+b)+b , 2b+1 = 7 and so b = 3
Therefore a is 7 = a+3 and so a = 4

Putting all these together we get:

4x^2 + 3x + 1 = 0