Answer to Question #94017 in Discrete Mathematics for Daniel

Question

3.The sets (A-B), \\(A\\cap B\\) and (B-A) are mutually disjoint implies…
a.the difference of any two is the null set
b.the intersection of any two is the null set
c.the union of any two is the null set
d.None of the option

4._____ is the set of elements which are common to A and B, that is, those elements which belong to A and which belong to B.
a.The difference of Sets A and B
b.The union of sets A and B
c.The intersection of sets A and B
d.The compliment of sets A and B

Answer 1

1. Let's take two sets,

$$A=\{1,2,3,4,5\} , B=\{1,2,3\}$$

$$A-B= \{1,2,3,4,5\}-\{1,2,3\}= \{4,5\}$$

$$B-A=\{1,2,3\}-\{1,2,3,4,5\}=\{\}$$

$$A\cap B=\{1,2,3\}$$

Answer: b.the intersection of any two is the null set 

4.The intersection of sets A and B is the set of elements which are common to A and B, that is, those elements which belong to A and which belong to B.

Answer: c.The intersection of sets A and B