# Thread: computing sets

1. ## computing sets

Can someone help me out with the following question?

A= {1,3,5,6} and B={3,5} and C={a,b,c}

Compute:

a. A-B = {1,6}
b. B X C ( X meaning Cartesian Product) {(3,a),(3,b),(3,c),(5,a),(5,b),(5,c)}
c. A $A\cap B$ (B-A)
d. A $A\Delta B$ {1,6}

can anyone help me with 3.

2. Originally Posted by wonderstrike
A= {1,3,5,6} and B={3,5} and C={a,b,c}
Compute:
a. A-B
b. B X C ( X meaning Cartesian Product) * this one confuses the heck outta me
c. A Intersection (B-A)
d. A symmetric difference B
ps, how do I do the upside down U and symetric difference signs?
$$A\cap B$$ gives $A\cap B$
$$A\cup B$$ gives $A\cup B$
$$A \times B$$ gives $A \times B$
$$A\Delta B$$ gives $A\Delta B$ symmetric difference.

3. Can I have help with c.

the way I understand is i need to do (B-A) 1st.

Well B-A is leaving me with nothing...

4. $A \cap \left( {B\backslash A} \right) = A \cap \left( {B \cap A^c } \right) = \emptyset$

$$A^c$$ is the complement of A, all elements not in A.

5. Originally Posted by Plato
$A \cap \left( {B\backslash A} \right) = A \cap \left( {B \cap A^c } \right) = \emptyset$

$A^c$ is the complement of A, all elements not in A.
Right.. so $\emptyset$ means that they are disjoint right?