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Inverse of cubic functions

by devious_
Tags: cubic, functions, inverse
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Oct11-04, 05:43 AM
P: 347
Is there a way (algebraic or otherwise) to find the inverse function of a cubic polynomial?

For example:
y(x) = x+x-9
y-1(x) = ?
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Oct11-04, 07:08 AM
Sci Advisor
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P: 1,123
Yes but it is big and nasty.

In the same way you can have:

[tex]y = ax^2 + bx + c[/tex]

[tex]ax^2 + bx + (c - y) = 0[/tex]

[tex]x = \frac{-b \pm \sqrt{b^2 - 4a(c-y)}}{2a}[/tex]

You can do it for cubic equations with this equation:
Oct11-04, 10:03 AM
P: 347
Thanks. Just what I was looking for.

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