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

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

Question

A = {positive integers} and B = {integers}, what is A ∩ B?
 	
	{1, 2, 3, 4, ...}
	{ }
	{...−3, −2, −1, 0, 1, 2, 3, ...}
	{0}

jim_thompson5910 · Answer

can you list some numbers that are in set A?

anonymous · Answer

Positive numbers like 1,2,3,4

jim_thompson5910 · Answer

good, how about set B?

anonymous · Answer

-3,-2,-1???

jim_thompson5910 · Answer

we can also have positive integers, alongside negative ones

jim_thompson5910 · Answer

so let's say 

B = {..., -3, -2, -1, 0, 1, 2, 3, ...}

also we have 0 in there too

jim_thompson5910 · Answer

so far, we know

A = {1, 2, 3, 4, ...}

B =  {..., -3, -2, -1, 0, 1, 2, 3, ...}

now what is common to both sets?

anonymous · Answer

1,2,3

jim_thompson5910 · Answer

and notice how I put in the ... dots

jim_thompson5910 · Answer

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

anonymous · Answer

Okay so also 4

jim_thompson5910 · Answer

So the answer is {1, 2, 3, 4, ...}

that's really set A

jim_thompson5910 · Answer

5 is included, 6 as well, etc etc

jim_thompson5910 · Answer

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

jim_thompson5910 · Answer

refresh the page if you get weird looking boxes or symbols

anonymous · Answer

Thanks