# Inverse of cubic functions

by devious_
Tags: cubic, functions, inverse
 P: 347 Is there a way (algebraic or otherwise) to find the inverse function of a cubic polynomial? For example: y(x) = x³+x-9 y-1(x) = ?
 Sci Advisor HW Helper P: 1,123 Yes but it is big and nasty. In the same way you can have: $$y = ax^2 + bx + c$$ $$ax^2 + bx + (c - y) = 0$$ $$x = \frac{-b \pm \sqrt{b^2 - 4a(c-y)}}{2a}$$ You can do it for cubic equations with this equation: http://www.math.vanderbilt.edu/~schectex/courses/cubic/
 P: 347 Thanks. Just what I was looking for.

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