Question

If A = {positive integers} and B = {…,−4, −3, −2, −1} what is A ∩ B

Answer 1

which do you think?

Answer 2

{…, −3, −2, −1, 1, 2, 3, …}

Answer 3

remember A is all positive integers
B seems all negative integers

∩ means intersection

Answer 4

{…−3, −2, −1}

Answer 5

do you see -3, -2, -1 in "all positive integers" ?

Answer 6

{1, 2, 3, 4, …}

Answer 7

i believe now you have a 50:50 chance if you're right ;) what do you think?

Answer 8

{ }

Answer 9

right