Question

MEDAL!! Find the union. Let A = {2, 5}, B = {5, 7, 9}, and C = {x | x is an odd number less than 9}, and D = {x | x is an even number less than 9}.

A \(\cup\) C

Answer 1

@Michele_Laino @freckles

Answer 2

the union of two sets, A and B, is the set of the elements contained in set A \(or\) in set B, so we have:
\[\Large A \cup B = \left\{ {2,5,7,9} \right\}\]

Answer 3

So for this question, can I have my answer as {5, 2, 1, 0, -1 ...}

Answer 4

I think that the sets C and D have to be subset of \(A \cup B\)

Answer 5

What do you mean?

Answer 6

I mean this:
\[\Large \begin{gathered}
C = \left\{ {5,7} \right\} \hfill \\
D = \left\{ 2 \right\} \hfill \\
\end{gathered} \]

Answer 7

I still don't know how to answer this question...

Answer 8

for example, numbers 5, 7 are odd numbers and less than 9

Answer 9

so, we got the set C

Answer 10

namely, I think that in order to solve the exercise, we have to do these steps:
1) to write the set \(A \cup B\)
2) to write the sets C and D, based on set \(A \cup B\)

Answer 11

But why do we need to do that when we need to find all of the elements in A or C? A = {2,5} and C = all odd numbers less than 9. So I just thought that since my teacher said the ellipses need to go after the integers are written, that I order it from greatest to least A \(\cup\) C = {5, 2, 1, 0, -1...}

Answer 12

please note that sets C and D are subsets of a more general set, I think, so you have to specify what is such more general set, otherwise I think that such more general set is \(A \cup B\)

Answer 13

okay thank you!

Answer 14

so, are C and D subset of the set of integers?

Answer 15

C and D would have an infinite amount of elements

Answer 16

odd={..,-5,-3,-1,1,3,5,...}
even={...,-6,-4,-2,0,2,4,6,...}

Answer 17

if they are subsets of the set of integers, yes! I think so!

Answer 18

C={...,-5,-3,-1,1,3,5,7}
D={...,-6,-4,-2,0,2,4,6,8}

Answer 19

We aren't given C and D are subsets of any sets so I feel that we must assume the most general set that they are subsets of

Answer 20

...they are subsets of integers, ok! :)