Results 1 to 4 of 4

Math Help - Inverse Function

  1. #1
    Junior Member
    Joined
    Jun 2010
    Posts
    35

    Inverse Function

    f(x)=4x+6; g(x)=x/4-6 is the function inverse of eachother.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member eumyang's Avatar
    Joined
    Jan 2010
    Posts
    278
    Thanks
    1
    \begin{aligned}<br />
f(x) &= 4x+6 \\<br />
g(x) &= \dfrac{x}{4} - 6<br />
\end{aligned}

    I guess you want to know if f(x) and g(x) are inverses of each other? If
    f(g(x)) = x and g(f(x)) = x then the answer is yes.

    I'll setup both for you.
    f(g(x))= 4\left( \dfrac{x}{4} - 6 \right) + 6
    ...
    Will f(g(x)) = x?

    And
    g(f(x))= \dfrac{4x + 6}{4} - 6
    ...
    Will g(f(x)) = x?
    Last edited by mr fantastic; August 11th 2010 at 05:35 AM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member masoug's Avatar
    Joined
    Aug 2010
    From
    Earth
    Posts
    30

    Talking

    The very best way is to take one of the functions and "plug" it into the other
    So in this case, f(x)=4x+6 and g(x)=\frac{x}{4}-6, f(g(x)) must equal x.

    So the inverse of f(x)=4x+6 should be:
    g(x)=\frac{x-6}{4}

    Checking that would be:
    f(x)=4(\frac{x-6}{4})+6
    Cancel out the four,
    f(x)=x-6+6
    And simplify,
    f(x)=x
    and so it checks, g(x)=\frac{x-6}{4} is the inverse function.

    -Masoug
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Jun 2010
    Posts
    35
    Quote Originally Posted by eumyang View Post
    Uhm, this is not a geometry question.

    \begin{aligned}<br />
f(x) &= 4x+6 \\<br />
g(x) &= \dfrac{x}{4} - 6<br />
\end{aligned}

    I guess you want to know if f(x) and g(x) are inverses of each other? If
    f(g(x)) = x and g(f(x)) = x then the answer is yes.

    I'll setup both for you.
    f(g(x))= 4\left( \dfrac{x}{4} - 6 \right) + 6
    ...
    Will f(g(x)) = x?

    And
    g(f(x))= \dfrac{4x + 6}{4} - 6
    ...
    Will g(f(x)) = x?

    Thanx
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. function composition and inverse function
    Posted in the Discrete Math Forum
    Replies: 7
    Last Post: November 10th 2009, 12:18 PM
  2. Replies: 2
    Last Post: October 19th 2009, 02:47 AM
  3. Replies: 2
    Last Post: September 22nd 2009, 08:29 PM
  4. Replies: 0
    Last Post: July 19th 2008, 08:06 PM
  5. Replies: 4
    Last Post: March 17th 2008, 09:45 PM

Search Tags


/mathhelpforum @mathhelpforum