Math Is Fun Forum

mathland

Member

Registered: 2021-03-25

Posts: 444

Testing For Function

Determine whether the table relation represents y as a function of x. Identify the domain and range.

Values of x.............Values of y

2..................................11
2..................................10
3....................................8
4....................................5
5....................................1

Let me see.

I know the following:

(x, y) = (input, output) = (domain, range).

From this, I can see that x = input = domain.
I also see that y = output = range.

If the input x has two different output y-values, there is no function.

I see that 2 is matched with 11 and 10. I say the above table does not represent a function. The table relationship does not represent y as a function of x.

Domain = {2, 2, 3, 4, 5}

Range = {11, 10, 8, 5, 1}

Bob

Administrator

Registered: 2010-06-20

Posts: 10,619

Re: Testing For Function

All correct!

B

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mathland

Member

Registered: 2021-03-25

Posts: 444

Re: Testing For Function

All correct!

B

Thank you Bob for not putting me down or picking fights. How do I block members on this site? I need to block two troublemakers. 

Thanks.

mathland

Bob

Administrator

Registered: 2010-06-20

Posts: 10,619

Re: Testing For Function

hi mathland,

I do my best.  If someone asks for help, they may get back a single reply or they may get several.  It's the Op's choice about which to use and which to ignore.  You don't need to make any comment at all to a reply that you don't think was helpful.

I joined in 2010 and began offering help.  A member (I'll call them A), who was also helping a poster, was very rude to me about my help.  I spent some thinking time constructing replies, some sarcastic, some rude, some just protesting my case.  In the end I decided not to reply at all.

Unknown to me at the time the moderators were having a private discussion about this.  They threatened member A with expulsion and the 'offending' post was edited.  Then MIF asked me if I would become a moderator.  His reason for choosing me was that I had maintained a polite and non heated position in the face of provocation. 

Moderators are able to do the following: (1) edit a post to remove unsuitable comments (2) delete a post entirely (3) close down a thread so that no subsequent posts can be made (4) ban a member (for a period or permanently) (5) delete all records of a member.

Administrators can do all that and also control the structure of the forum in a number of ways.

If you are unhappy about a post you should click the 'Report' button below the post, on the right.  This generates a report for moderators so they can consider what action to take.  Ordinary members cannot block other members.

This morning I have removed a number of unpleasant comments from the forum and deleted some posts entirely.  I have closed some threads.  It is my hope that the members effected will take this as a warning that they have made unacceptable comments and avoid this in future.  That way we can keep the forum as a pleasant and safe place for all.

Best wishes,

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mathland

Member

Registered: 2021-03-25

Posts: 444

Re: Testing For Function

hi mathland,

I do my best.  If someone asks for help, they may get back a single reply or they may get several.  It's the Op's choice about which to use and which to ignore.  You don't need to make any comment at all to a reply that you don't think was helpful.

I joined in 2010 and began offering help.  A member (I'll call them A), who was also helping a poster, was very rude to me about my help.  I spent some thinking time constructing replies, some sarcastic, some rude, some just protesting my case.  In the end I decided not to reply at all.

Unknown to me at the time the moderators were having a private discussion about this.  They threatened member A with expulsion and the 'offending' post was edited.  Then MIF asked me if I would become a moderator.  His reason for choosing me was that I had maintained a polite and non heated position in the face of provocation. 

Moderators are able to do the following: (1) edit a post to remove unsuitable comments (2) delete a post entirely (3) close down a thread so that no subsequent posts can be made (4) ban a member (for a period or permanently) (5) delete all records of a member.

Administrators can do all that and also control the structure of the forum in a number of ways.

If you are unhappy about a post you should click the 'Report' button below the post, on the right.  This generates a report for moderators so they can consider what action to take.  Ordinary members cannot block other members.

This morning I have removed a number of unpleasant comments from the forum and deleted some posts entirely.  I have closed some threads.  It is my hope that the members effected will take this as a warning that they have made unacceptable comments and avoid this in future.  That way we can keep the forum as a pleasant and safe place for all.

Best wishes,

Bob

1. Thank you, Bob

2. I accidentally clicked on "Report" at the bottom of your most recent reply (this one). It was an error.

3. You have no idea how many math sites I have joined and left due to troublemakers, you know, people picking fights and arguments.

4. I have idea how many countless times I posted my main reason for joining MIF.
Some "know it all" stated that my questions are too easy. The person went on to say that he does understand what my problem is in terms of math. I feel like challenging this fool by posting the toughest textbook problems specifically for him to help me with. This may teach him some humility.

5. How do I become a moderator here?

6. I still don't know how to upload pictures. Can you show me step-by-step?

7. I hope my contribution to MIF will help others who may be struggling and/or facing the same problems in their math class.

8. As you know, I am 56 years old. I have three college degrees in areas other than math. I took Precalculus in the Spring 1993 semester at Lehman College. I earned an A minus. Of course, this is long ago. So, I decided to revisit this course as I study Calculus 1 (also for the sake of learning). All this is just for fun. How do you think I made through the pandemic?

9. I love Precalculus. It is one of my favorite courses.

10. I will also contribute here as a math tutor by answering prealgebra, algebra 1, algebra 2, geometry and trigonometry questions (at the middle school and high school levels). Thus far, I have not seen too many recent middle school and high school math questions here (MIF).