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Math Help - How do you find a quadratic function?

  1. #1
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    Exclamation 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?
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by kcwillia377 View Post
    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<br />
    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
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