# Math Help - inverse one-one functions

1. after finding the inverse of a function algebraically how can you tell if its one-one without graphing on ti-83 and doing the horizontal line test?

take for instance the problem f(x)=3x+4/5

for the inverse i got 5x-4/3=y

from this how do i find the if its one-one without graphing

2. Originally Posted by purified
take for instance the problem f(x)=3x+4/5
for the inverse i got 5x-4/3=y
from this how do i find the if its one-one without graphing
Well all linear equations are one-to-one.
Beyond that, you will learn how to do this in basic calculus.
But in pre-calculus it is very difficult.

3. Your function is linear. All linear functions are one to one.

You should learn the shapes of each polynomial $x^n$ where $n \in \mathbb{J}$

4. like i understand f(x)=1/x^2 can not be one to one because x^2 will always be positive f(1)=f(-1)=1 but what about like:

f(x)=x^4
inverse: y=plus or neg nth root 4 squareroot X