E = {x : x is a prime number, which is a divisor of 42}.

Question

Write the following sets in roster from:

E = {x : x is a prime number, which is a divisor of 42}.

Answer 1

Prime number = Those number which is divisible by 1 and the number itself. 

Prime numbers are 2, 3, 5, 7, 11, 13, … 

Divisor of 42: 

42 = 1 × 42 

42 = 2 × 21 

42 = 3 × 14 

42 = 6 × 7 

So, divisors of 42 are 1, 2, 3, 6, 7, 14, 21, 42 

The elements which are prime and divisor of 42 are 2, 3, 7 

So, E = {2, 3, 7}