Question

If A = {x : x is a natural number } B = {x : x is an even number} C = {x : x is an odd number } D = {x : x is a prime number} then find A∪B,A∩C,B∩C and B ∩ D. Wbat do you notice ?

Answer 1

A = {x : x is a natural number} = {1,2,3, , } 

B = {x : x is an even number} = {2,4,6, } 

C = {x : x is an odd number} . = {1,3,5, …} 

D = {x : x is a prime number = {2,3,5, } 

A ∪ B = {1, 2, 3 …………}{2, 4, 6……………. } = {1,2,3……………} 

A ∩ C = {1, 2, 3…………. } ∩ {1, 3, 5………….. } = {1, 3, 5………….. } 

B ∩ C = {2,4,6……. }∩{1,3,5……….. } = {} = ø 

B ∩ D = {2,4,6,…} ∩ {2,3,5,…} = {2} 

Noticed that A∪ B = A 

A ∩ C = C