Turn on thread page Beta

What does f:x-> mean? Mathematics notation watch

    • Thread Starter
    Offline

    16
    ReputationRep:
    I'm currently doing some C3 and have noticed the notation f: x -> appear a few times, please can someone help with with what this means?

    also could I for instance substitute in Y for f:x ->
    • Community Assistant
    Offline

    18
    ReputationRep:
    Community Assistant
    (Original post by NoahMal)
    I'm currently doing some C3 and have noticed the notation f: x -> appear a few times, please can someone help with with what this means?

    also could I for instance substitute in Y for f:x ->
    The function f is such that each value of x maps onto...
    It is basically the same as f(x) for c3.

    so f: x -> x^2 means f(x) =x^2
    Offline

    17
    ReputationRep:
    Just means f is a function of x
    Offline

    14
    ReputationRep:
    It's the right notation for a function.

    Functions are defined from a domain to a codomain (C3 probably calls it the range, if I remember). This notation is quite explicit about it from this point of view: f : [thing in domain] -> [thing in codomain]. Technically, it should specify what the domain and range are, but during A levels, these are exclusively \mathbb{R} and \mathbb{R}^{>0} (i.e., real numbers, and positive real numbers).

    Why do I say this is the right notation? Because whenever you write things like f(x), you should be aware that the function is f, not
    f(x). f(x) is the result of having applied f to x. It is a member of the codomain!! To be more precise about the connection between these two notations, you can write (unhelpfully) f : x \rightarrow f(x) . That obviously tells you nothing about the function, but it shows you what the point is.

    As a concrete example, you should simply think of f(x)=x^2 as a function on real numbers as a shorthand for f:\mathbb{R}\rightarrow \mathbb{R},\ x\rightarrow x^2
 
 
 
The home of Results and Clearing

2,802

people online now

1,567,000

students helped last year

University open days

  1. Sheffield Hallam University
    City Campus Undergraduate
    Tue, 21 Aug '18
  2. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  3. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
Poll
A-level students - how do you feel about your results?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

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