Question

Which relation is a function?

A {(1, 2); (2, 3); (3, 4); (4, 5)}
B {(1, 2); (1, 3); (1, 4); (1, 5)}
C {(1, 2); (2, 3); (3, 4); (2, 5)}
D {(1, 2); (3, 2); (3, 3); (4, 2)}

Answer 1

http://openstudy.com/study#/updates/5314f53de4b09b97a185fdf2

Answer 2

you didn't answer my question

Answer 3

well, that's what you're supposed to do :)

Answer 4

i don't know how, that's the thing

Answer 5

the 1st number of each pair is the "x"
the 2nd number of each pair is the "y"

so by no x-repeats, I meant
the 1st number of each pair cannot have any repeats for a function

Answer 6

i still don't get it

Answer 7

ok... lemme \(\bf A {(1, 2);\quad (2, 3);\quad (3, 4);\quad (4, 5)}\\
B {(1, 2);\quad (1, 3);\quad (1, 4);\quad (1, 5)}\\
C {(1, 2);\quad (2, 3);\quad (3, 4);\quad (2, 5)}\\
D {(1, 2);\quad (3, 2);\quad (3, 3);\quad (4, 2)}\)

notice the 1st number of each pair
which set or line doesn't have any repeated 1st number per line?

Answer 8

ummm, C?

Answer 9

let's take a peek at C \(\bf A {(1, 2);\quad (2, 3);\quad (3, 4);\quad (4, 5)}\\
B {(1, 2);\quad (1, 3);\quad (1, 4);\quad (1, 5)}\\
C {(1, 2);\quad ({\color{red}{ 2}}, 3);\quad (3, 4);\quad ({\color{red}{ 2}}, 5)}\\
D {(1, 2);\quad (3, 2);\quad (3, 3);\quad (4, 2)}\)

hmm we have one repeated "x" or 1st number, so is not that one

Answer 10

Hmmm A?

Answer 11

\(\bf A {({\color{blue}{ 1}}, 2);\quad ({\color{blue}{ 2}}, 3);\quad ({\color{blue}{ 3}}, 4);\quad ({\color{blue}{ 4}}, 5)}\quad \checkmark\\
B {(1, 2);\quad (1, 3);\quad (1, 4);\quad (1, 5)}\\
C {(1, 2);\quad (2, 3);\quad (3, 4);\quad (2, 5)}\\
D {(1, 2);\quad (3, 2);\quad (3, 3);\quad (4, 2)}\)

Answer 12

so, A set is a function

Answer 13

Thank you !

Answer 14

yw