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

{ }

{…, −3, −2, −1, 1, 2, 3, …}

{1, 2, 3, 4, …}

{…−3, −2, −1}

Question

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

lgbasallote · Answer

set A is all positive integers

set B is all negative integers

so what would be the common numbers?

anonymous · Answer

1,2,3,...?

lgbasallote · Answer

do you see 1, 2, 3 in negative integers?

lgbasallote · Answer

remember negative integers are -1,  -2, -3, ...

compassionate · Answer

They can both have the ±0

anonymous · Answer

{…, −3, −2, −1, 1, 2, 3, …}?

lgbasallote · Answer

@ineedhelp1011111 that is union since you combine both elements. $\cap$ means you find a number COMMON to BOTH sets.

lgbasallote · Answer

@Compassionate there's no such thing as $\pm 0$ 0 is neither positive nor negative. it is a neutral number. there is however $\large 0^\pm$ but that's different lol

anonymous · Answer

so i got it wrong? O.o

lgbasallote · Answer

probably

anonymous · Answer

im confused

lgbasallote · Answer

$\cap$ means intersection. what you wrote is union. union is when you put all the numbers of one set. and the numbers of the other set. all in one set. 

intersection is just writing the common numbers

for example

A{1,2,3,4,5} and B{2,4,6,8}

A U B would just be {1,2,3,4,5,6,8}

because you just put all the numbers in both sets

A$\cap$ B would be {2,4,6} because both A and B has 2, 4 and 6

got it?

anonymous · Answer

yes i got it, but the equation i put above would be [ ]?

lgbasallote · Answer

right!

lgbasallote · Answer

when there are no elements common you put {}

anonymous · Answer

thanks

lgbasallote · Answer

welcome