(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Show f and g are inverse functions or state that they are not.

f(x)= cube root of -8x-6 g(x)= -(x^3+6)/(8)

2. Relevant equations

You find inverses by plugging the equations into each other, if they are inverses then once you simplify the composed equation, it will equal x.

3. The attempt at a solution

cube root of {-8[-(x^3+6)/(8)]-6} I plugged g(x) into f(x) now I need to solve it, this is what I did but its not right because the answer should come out to be just x.

I multiplied everything by 8 to get it out of the denominator and simplified the numerator which left me with

cube root of {64x^3-432}

then I thought maybe you could pull out the 64 and x^3 from the cube root to get

4x times the cube root of {-432}

which is definitely not going to = x not matter what I do to it.

I feel a bit stupid for not being able to solve this because the solving is not supposed to be the challenge, the concept of what makes the functions of inverses is. I think I've just forgotten how to solve harder equations.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Solving functions algebraically (cube roots)

**Physics Forums | Science Articles, Homework Help, Discussion**