# Functions and mappings

Watch
#1
Hi there,

For this question, it asks whether this mapping is one-to-one, many-to-one or one-to-many.

I thought one-to-many, however the solution bank for the textbook (Edexcel) tells me one-to-one.

Does anyone know the correct answer, and could clear this up for me please?

Thank you!

Attachment 949816
Last edited by Dan Silverman; 7 months ago
0
7 months ago
#2
(Original post by Dan Silverman)
Hi there,

For this question, it asks whether this mapping is one-to-one, many-to-one or one-to-many.

I thought one-to-many, however the solution bank for the textbook (Edexcel) tells me one-to-one.

Does anyone know the correct answer, and could clear this up for me please?

Thank you!
Actually, this is many-to-one.

You can use horizontal/vertical line tests to determine this if you have trouble just by looking at it.

You can learn it here:

https://www.chilimath.com/lessons/in...cal-line-test/
https://www.chilimath.com/lessons/in...tal-line-test/

In brief, if your mapping passes the vertical line test, then your mapping is a function (i.e. either one-to-one, or many-to-one).

If your mapping passes the horizontal line test, then your mapping is injective (i.e. one-to-one).

Mappings which pass both tests must necessarily be one-to-one.
Last edited by RDKGames; 7 months ago
0
#3
(Original post by RDKGames)
Actually, this is many-to-one.

You can use horizontal/vertical line tests to determine this if you have trouble just by looking at it.

You can learn it here:

https://www.chilimath.com/lessons/in...cal-line-test/
https://www.chilimath.com/lessons/in...tal-line-test/

In brief, if your mapping passes the vertical line test, then your mapping is a function (i.e. either one-to-one, or many-to-one).

If your mapping passes the horizontal line test, then your mapping is injective (i.e. one-to-one).

Mappings which pass both tests must necessarily be one-to-one.
Thank you! I meant many-to-one but thank you for clearing this up and sharing those links with me. The solution bank for my textbook told me a different answer - confusing me. Have a good evening!
0
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### What factors affect your mental health the most right now?

4.62%
Uncertainty around my education (196)
15.36%
Uncertainty around my future career prospects (141)
11.05%
Lack of purpose or motivation (181)
14.18%
Lack of support system (eg. teachers, counsellors, delays in care) (57)
4.47%
Impact of lockdown on physical health (72)
5.64%
Loneliness (112)
8.78%
Financial worries (45)
3.53%
Concern about myself or my loves ones getting/having been ill (58)
4.55%
Exposure to negative news/social media (58)
4.55%
Lack of real life entertainment (68)
5.33%
Lack of confidence in making big life decisions (112)
8.78%
Worry about missed opportunities during the pandemic (117)
9.17%