Is there a simpler solution for finding the inverse of a cubic function?

  • Context: Undergrad 
  • Thread starter Thread starter agricola
  • Start date Start date
  • Tags Tags
    Inverse
Click For Summary
SUMMARY

The discussion centers on the challenge of finding an analytic solution for the inverse of a cubic function represented by the equation p=ax^3+bX^2+cX. The participants confirm that while a general formula exists for cubic equations, it is highly complex and may not yield a straightforward inverse. The function is noted to be positive monotonic under specific conditions for the coefficients a, b, and c, which ensures the cubic function maintains a single direction without turning back.

PREREQUISITES
  • Understanding of cubic functions and their properties
  • Familiarity with the concept of monotonicity in mathematical functions
  • Knowledge of analytic solutions for polynomial equations
  • Experience with plotting functions to visualize behavior
NEXT STEPS
  • Research the general formula for cubic equations and its applications
  • Explore methods for visualizing cubic functions and their inverses
  • Study the implications of monotonicity on the existence of inverses
  • Learn about numerical methods for approximating inverses of complex functions
USEFUL FOR

Mathematicians, educators, and students studying polynomial functions, particularly those interested in the properties and inverses of cubic equations.

agricola
Messages
1
Reaction score
0
p=ax^3+bX^2+cX is positive monotonic and has an inverse X=G(p)

But I can't invert it. Is there an analytic solution?
For given parameter values I can plot numeric values- it has a tilted S shape.
 
Mathematics news on Phys.org
This is, by the way, a "cubic" equation, not "quartic". I take it, you mean by "is positive monotonic" that you are assuming values of a, b, and c such that the function is monotonic. Of course a cubic equation cannot always be positive. A true "quartic" (fourth degree) equation can but it cannot be monotonic.

There is a general formula for solutions to cubic equations that could, theoretically, give an inverse function for this, but it is extremely complicated.
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 16 ·
Replies
16
Views
5K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
964
Replies
10
Views
6K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
5
Views
2K