Question

@phi
I also would like to understand this one as well.

Answer 1

a function has two parts: the domain and the range
for each number in the domain you are allowed only 1 number from the range.
in other words, only 1 value can be matched to the domain number.

Answer 2

if we start with "tree heights"
For example, say we have 3 trees and they all have the same height 10 feet
and we give the trees a number 1,2,3

we could then form the pair (tree height, tree number)
(10,1), (10,2), (10,3)

notice that the domain number 10 has 3 different numbers for the range.
that means we do NOT have a function.

Answer 3

I see; that makes sense.

Answer 4

for choice B, domain= car make and range = people

if we pick domain Toyota, it should be obvious different people can own a toyota, and we can form pairs
(toyota, fred), (toyota, lil), etc.
we get two different values for the range, so this is not a function.

Answer 5

the last choice, social security number for the domain, and people for the range
you can look at a social security number, and find the one and only person who was assigned that number. this makes it a function.

Answer 6

ah; thank you.