Question

1. Define:Union set and intersection set
2. Draw the venn diagram of A union B, A intersection B and A-B, B-A
3. If n(A)=6, n(B) =5 and n(AUB)=9 then find n(A nB)
4.If A={1, 2,3,4,5,6}, B={1, 2,3,4,5,6,7,8} then find A-B and B-A
5.write the set in the set- builder form{5, 25,125,625}​

Answer 1

Answer:

1. The union of two sets contains all the elements contained in either set (or both sets). The union is notated A ⋃ B. More formally, x ∊ A ⋃ B if x ∊ A or x ∊ B (or both) The intersection of two sets contains only the elements that are in both sets. The intersection is notated A ⋂ B.

3. n(A∪B)=n(A)+n(B)−n(A∩B)−−−−−−−(1)

Given n(A)=7

n(B)=9

n(A∪B)=14

Substituting in 1

14=7+9−n(A∩B)

⇒n(A∩B)=16−14=2

5. (5,25,125,625)

It can be seen that 5=5¹

,25=5²

,125=5³

and 625=5⁴

∴(5,25,125,625) = {x:x=5^4,nϵN and 1≤n≤4}.