Question

Which sets of numbers are closed under addition?

Choose all answers that are correct.

A.
{0, 2, 5, 8}

B.
even integers

C.
rational numbers

D.
{0}

Answer 1

Medal and Fan!!!!!!!

Answer 2

if the sum of any 2 numbers in the set does not equal a member of the set then its not closed under addition

Answer 3

so do you think the first set is closed under addition?

Answer 4

umm......hmmmm yes?

Answer 5

5 + 8 = 13
is 13 a member of the set?

Answer 6

A is not closed under addition

Answer 7

What he means is if you add 2 numbers together in the set, and if it equals a number inside the set, then it is closed under addition, and if the value is not a number in the set, it is not closed under addition.

Answer 8

Same with subtraction, division and multiplication.

Answer 9

*she plz

Answer 10

oh ok so its a and b?

Answer 11

no - we have just shown that A is NOT closed under addition

Answer 12

B is closed because if you take any 2 even integers and add them the result will always be another even integer

Answer 13

a is not closed under addition because 5 + 8 = 13 and 13 is not a member of the set

Answer 14

get it?

Answer 15

Now for B, if you take an even number and add it by an even number you will get an even number so B is correct. Is there another one that is correct?

Answer 16

Look at C. What happens when you take a rational number and add another rational number? Do you always get another rational number?

Answer 17

so c is correct too? @MDoodler

Answer 18

@TheEdwardsFamily - do you see why A is not closed ?

Answer 19

yes C is correct - you'll always get a rational number when you add in this set

Answer 20

They have a real problem with thiere user interface. It is hard to submit anything when you get to the bottom of the browser

Answer 21

@TheEdwardsFamily A is not correct. B is correct. C is correct too

Answer 22

yes - you can't press the blue POST box ?

Answer 23

No I cannot

Answer 24

If I use IE, it wants me to download a Javascript file

Answer 25

whats the blue post box???

Answer 26

OK hold down Shift and Tab together and Press ENter That should do it

Answer 27

Ok thank you!!

Answer 28

HAHA shift and tab gives me their Ajax code

Answer 29

@TheEdwardsFamily - the pace where you click to post an answer

Answer 30

On Chrome

Answer 31

yea I'm on chrome I dont like IE

Answer 32

I like IE 11, which is the first IE I have ever liked

Answer 33

On Chrome, when I use shift and tab it pops up their ajax code

Answer 34

Hmmm try again

Answer 35

Hmm

Answer 36

tab and enter does the trick. Just testing
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Answer 37

oh ok