Thread: Inverse functions

How do I find f^-1 (2), x for f^-1 (x) = 0

I have a graph with a function f on it,

f(x) = [ 2x^3 + 1/2 x + 5 ]/2



And also, it would be great if someone could find the equation for the inverse of f(x)

Originally Posted by realintegerz

How do I find f^-1 (2), x for f^-1 (x) = 0

I have a graph with a function f on it,

f(x) = [ 2x^3 + 1/2 x + 5 ]/2



And also, it would be great if someone could find the equation for the inverse of f(x)

Remember that for inverses the domain and range switch. For example

has domain A and range B than has domain B and range A

Ok so using this info we can solve what and is since we know the function is





1) is

so





2)To solve the other problem set



and solve for x

hmmm..

im stuck on that f^-1 (2)...

So far i simplified it to...

-2 = 4x^3 + x

Originally Posted by realintegerz

hmmm..

im stuck on that f^-1 (2)...

So far i simplified it to...

-2 = 4x^3 + x

i tried using the rational root theorem but couldn't get any nice roots so i used the cubic equation. You could also do it numerically.

Originally Posted by 11rdc11

i tried using the rational root theorem but couldn't get any nice roots so i used the cubic equation. You could also do it numerically.

I know the quadratic equation..but not cubic...

could you explain that?