Question

Question regarding onto and one to one

Answer 1

My answers were the following, can you guys tell me if it is valid?
a) 2x
b) x/2
c) x

Answer 2

@armmonipowtoon @SweetPeaGirl @i_luv_donuts

Answer 3

in your own words, how do you define 1-1 and onto ?

Answer 4

and typically, n is used instead of x for the set of integers i beleive

x is a real variable, n is a discrete variable

Answer 5

n/2 is not onto, it is into ... onto, and correct me if im wrong, means that we cover the whole range.

Answer 6

something like a shifted n^2 is onto, but you have more than 1 domain going to a range

Answer 7

(n-2)^2

assuming 0 is in N, depends on the text/course

if not add 1

Answer 8

well, the way i understood it was, onto means atleast 1 y value for every x and one to one is at most 1 y value for every x value.

Answer 9

right, but all of the range has to be hit by the domain

Answer 10

and for part b) the domain is all whole numebrs. so, if it was x/2, then every y value would be, at some point, covered.

Answer 11

there is no y, that cannot be hit by a domain value is there?

Answer 12

there are domain values which do not hit a range value

Answer 13

3/2 is not in the range

Answer 14

Hmmm, is that also a requirement?

Answer 15

if we are mapping the domain onto the range, then im sure it is

Answer 16

so what would work for being onto but not 1-1 in that domain?

Answer 17

something that is not invertible, like a quadratic works,

Answer 18

but quadratic doesn't cover negative y values up to negative infinity?

Answer 19

since 0 is defined in your work is a member of N

(n-2)^2 is onto

but n=0 and n=4 are both 4

Answer 20

oh, is a Z your in

Answer 21

text too large is sometimes as bad as text to small :)

Answer 22

cubics work

Answer 23

n(n+1)(n-1) should form some nice hooks

Answer 24

but is it onto ?

Answer 25

into, means that we can ignore some range values .. onto means we cover them