Question

If A = {2, 4, 6, 8, 10} and B = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, what is A U B ?

Answer Choices-

{2, 4, 6, 8, 10}

{1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 8, 8, 9, 10, 10}

{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

{ }

Answer 1

its the third choice
note that elements common to both sets are only written once

Answer 2

Is that how I should answer future questions similar to this, by eliminating answer choices based on the number of elements that repeat?

Answer 3

yup AUB is elements of A+ elements of B
n the common elements appear only once :)

Answer 4

right

Answer 5

Ok, and how about one like this:

If A = {negative integers} and B = {integers divisible by 3}, what is A ∩ B?

{…−4, −3, −2, −1}

{ }

{…−12, −9, −6, −3}

{0}

Would the answer be- The Third one again?

Answer 6

And also these:

If S = {integers} and subset B = {positive integers}, what is B'?

{…,−3, −2, −1}

{integers} - I think this is the answer.

{ }

{1, 2, 3, 4, …}

Answer 7

the last post but one
yes 3rd is correct

Answer 8

ok, can you help explain why?

Answer 9

oh sorry - its B' not B.

B' means the elements not in B

Answer 10

answr is integers

as integers can be positivve as well as negative

Answer 11

- that is the negative integers
that is {…,−3, −2, −1}

Answer 12

So the final answer for that questions is {Integers}.
Correct?

Answer 13

no

Answer 14

set S is all integers - that is positive and negative integers
B is a subset of S - positive integers
and B' is all integers in S EXCEPT positive integers
- i e negative integers
{..., -3, -2, -1}

Answer 15

Oh ok, so when it says subset it means its the part of S that's not there, the positive integers are already there so whats missing is the negative integers.

Answer 16

a subset is a 'set within a set'
heres an example A = {2,3} is a subset of B ( 1, 2 , 3 , 5. 6}