What is the inverse of the function

In summary, the conversation is about solving for y in terms of x in the equation x=ay+by^3. Two methods are suggested, one involves substituting y with a new variable z and solving for z, while the other involves using a trigonometric identity and comparing coefficients. These methods are commonly used to solve cubic equations when the second degree term is missing.
  • #1
kmarinas86
979
1
I'm running out of ideas:

[tex]x=ay+by^3[/tex]

Does someone here now how to solve for [tex]y[/tex] in terms of [tex]x[/tex]?
 
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  • #2
[tex]y^3 + \frac{a}{b}y - \frac{x}{b} = 0[/tex]

Two ways :

1) Substitute [tex]y = z - \frac{a}{3bz}[/tex]. Form a quadratic in [tex]z^3[/tex], solve for z and find y.

2) Compare equation to the trig identity [tex]cos^3 \theta - \frac{3}{4}\cos\theta - \frac{1}{4}\cos 3\theta = 0[/tex] while letting [tex]y = m\cos\theta[/tex] then comparing coefficients. With this method, if you have to compute the arccosine of a value greater than one in magnitude, use the identity [tex]\cos i\theta = \cosh \theta[/tex]

These are methods used to solve the general cubic in radicals/trig/hyperbolic trig ratios when the second degree term is missing (or has been eliminated).
 
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FAQ: What is the inverse of the function

What does the term "inverse function" mean?

The inverse of a function is another function that undoes the original function. It is denoted by f^-1(x) and is defined as the input-output relationship where the inputs of the original function become the outputs of the inverse function and vice versa.

How do you find the inverse of a function?

To find the inverse of a function, you can follow these steps:1. Write the original function in the form y = f(x)2. Swap the x and y variables in the equation.3. Solve for y to get the inverse function in the form x = f^-1(y)4. Replace y with f^-1(x) to get the final inverse function.

What is the importance of inverse functions?

Inverse functions are important because they allow us to solve equations where the input and output are swapped. They are also useful in finding the roots of an equation and in solving systems of equations. Additionally, they help in understanding the behavior of a function and its inverse.

Can every function have an inverse?

No, not every function has an inverse. A function must be one-to-one, meaning every input has a unique output, for it to have an inverse. If there are multiple inputs that give the same output, then the inverse cannot be defined.

How do you know if a function has an inverse?

A function has an inverse if it passes the horizontal line test, meaning no horizontal line intersects the graph of the function more than once. This ensures that each input has a unique output and the inverse can be defined.

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