Question

A = {positive integers} and B = {integers}, what is A ∩ B?

{1, 2, 3, 4, ...}
{ }
{...−3, −2, −1, 0, 1, 2, 3, ...}
{0}

Answer 1

can you list some numbers that are in set A?

Answer 2

Positive numbers like 1,2,3,4

Answer 3

good, how about set B?

Answer 4

-3,-2,-1???

Answer 5

we can also have positive integers, alongside negative ones

Answer 6

so let's say

B = {..., -3, -2, -1, 0, 1, 2, 3, ...}

also we have 0 in there too

Answer 7

so far, we know

A = {1, 2, 3, 4, ...}

B = {..., -3, -2, -1, 0, 1, 2, 3, ...}

now what is common to both sets?

Answer 8

1,2,3

Answer 9

and notice how I put in the ... dots

Answer 10

that means the set keeps going on forever following the same pattern

Answer 11

Okay so also 4

Answer 12

So the answer is {1, 2, 3, 4, ...}

that's really set A

Answer 13

5 is included, 6 as well, etc etc

Answer 14

turns out that because A is a subset of set B, this means A ∩ B = A

Answer 15

refresh the page if you get weird looking boxes or symbols

Answer 16

Thanks