Turn on thread page Beta
    • Thread Starter

    f(x)=1/x ( X≤3) X is real

    can someone show me how to do the inverse function domain and range,


    These are the steps i follow to find the inverse function.
    Change the f(x) to Y....
    Y = 1/x

    Swap the X and the Y's around (this makes no sense mathamatically, but it works!)
    X = 1/Y

    Now make Y the subject
    Y = 1/X
    F^-1(x) = 1/x

    lool, thats exactly the same! Therefore, there must be some other way of working it out...

    The inverse function's Domain is always the functions range, and the inverse functions range is always the
    The DOMAIN is a comment about the X values. for F(x), thats X<3 (as said in the question)
    Therfore the RANGE of the INVERSE is Y<3

    To find the range for f(x), draw out the graph of y = 1/x. Find a comment about the Y values for this graph. I think, whilst picturing it in my head, the range for f(x) is 0 > y > 0 (so basically Y can be any value except for 0)

    Now, this means that for the domain of the inverse is 0 > X > 0

    D of f(x) = R of INVf(x)
    R of f(x) = D of INVf(x)

    ^learn that, it's a good way of getting marks.

    Hope this is correct and helps!

    Edit: when drawing f(x), remember about the restriction [x<3]. The domain i've said for INVf(x) is incorrect because i forgot to take this into account. Hopefully you can come up with the domain urself.

    (Original post by AmyTownshend)
    f(x)=1/x ( X≤3) X is real

    can someone show me how to do the inverse function domain and range,

    y =\frac{1}{x}

    now swap the x and the y around and rearrange to make y the subject.

    You should get

    f^-^1 (x) = \frac{1}{x}

    Now the domain for the inverse function is the range of the original function and the inverse of this is the range of the original function
Submit reply
Turn on thread page Beta
Updated: September 25, 2011

University open days

  • University of Roehampton
    All departments Undergraduate
    Sat, 17 Nov '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 17 Nov '18
  • Bournemouth University
    Undergraduate Open Day Undergraduate
    Sat, 17 Nov '18
Black Friday: Yay or Nay?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here


How to use LaTex

Writing equations the easy way


Best calculators for A level Maths

Tips on which model to get

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.