Question

If A={1,2,3,4} and B={a,b,c} and S is a subset of A then find no. of onto functions from S->B

Answer 1

S can have 3 elements or 4 elements max

Answer 2

didn't get you,confused :/

Answer 3

\[\LARGE 4c3 \times 3!\]

Answer 4

24?

Answer 5

S1={1,2,3}
S2`={2,3,4}
S3={3,4,1}
S4={4,2,1}..and so on
why are we doing this?

Answer 6

Codomain=range?

Answer 7

You are confusing me sire.

Answer 8

That is not an onto function which you drew,its a many-one

Answer 9

but I want onto functions

Answer 10

you mean 32 functions?

Answer 11

In an onto function we must use every element of the second set and it must be a function. That means the first set must have at least as many elements as the second set otherwise we would have to use an element of the first set twice and then it would not be a function.

Answer 12

@hartnn

Answer 13

answer is 60

Answer 14

oh and its NOT bijective

Answer 15

no where stated that its one-one

Answer 16

onto+one-one means bijective!

Answer 17

onto DOESN'T mean bijective

Answer 18

yeah!

Answer 19

and its not 3^4

Answer 20

idk.

Answer 21

our subset can vary..there will be 2 cases

Answer 22

It is a subset of A
{1,2,3,4}
{1,2,3}
{1,2}
{1}
{}
{1,3,4}
{1,2,4}
{1,3}
{1,4}
{2,4}
..etc

Answer 23

but we can't accept all the subsets

Answer 24

answer is 60!

Answer 25

ah ! is not factorial :/

Answer 26

linear algebra stuff