Question

Which relations are functions?

Select Yes or No for each relation.

Relation Yes No

(2, 2), (3, 3), (4, 4), and (5, 5)

(1, 2), (1, 3), (1, 4), and (1, 5)

(2, 1), (3, 1), (4, 1), and (5, 1)

​(2, 2), (2, 3), (5, 4), and (5, 5)

Answer 1

Trace it out. See which one is a function. Do you know how to test for that? How to determine if a relation is a function?

Answer 2

i am sorry i dont but i think the first one is a relation

Answer 3

I'd say plot those points on paper, trace them with a pen. See if you can figure it out. Another rule is, one x is not allowed to have two y's.

Why?

Imagine you have a list of all students and their ages in a class, and one student is both an 18 year old and a 20 year old. Does that make any sense?

Answer 4

Yeah you're right! Student 1 Cannot be 2 year old, 3 year old, 4 year old, and 5 year old at the same time!

Answer 5

years not year ahah

Answer 6

One x is allowed to have only one y. 1 Student can have only 1 age.
Of course, there can be many students that have the same age, so different x's can have the same y.

Answer 7

you need to check only this: no repeats in the first numbers

Answer 8

for example
(2, 2), (3, 3), (4, 4), and (5, 5) is, because all the first numbers are different
ignore the second numbers, that has nothing to do with it

Answer 9

but arent the first number the same 2,2

Answer 10

by " first number" i mean the first number of each ordered pair \[(\text {first, second})\]

Answer 11

or if you prefer, all the \(x\) values have to be different, the ordered pairs are \((x,y)\)

Answer 12

ok like (2,2) and (5,5) the other 5 doesn't madder @satellite73

Answer 13

yeah see, if you have (1,1) you're OK.
But the FIRST number, (#,1) the first number CAN'T GET MORE THAN ONE VALUE
sooo
if you have (1,1) that's cool. But after that, if you have (1,2) it's not a function.