Question

Match the sets in the roster form with the description given.

• A. {1,2,3,4,6,12}
• B. {2,3}
• C. {2,4,6,8}
• D. {2,3,5,7}

Answer 1

Even numbers are those numbers divisible by 2. So, the set of even numbers which are strictly less than 10 are {2,4,6,8}. Note that 10 is not included because 10 is not strictly less than 10.
12 can be expressed as follows:
$12=1\times 12$
$12=2\times 6$
$12=3\times 4$

Thus, the set of factors of 12 are {1,2,3,4,6,12}

However, out of the given factors, only 2 and 3 are prime numbers. Hence, the set of prime factors of 12 is {2,3}

The set of prime numbers below 10 is {2,3,5,7} as only these numbers have just 2 factors(1 and the number itself).