Question

Identify a common factor for the set of integers.

{21, 91, 154, 217, 315}
A) 3
B) 7
C) 9
D) 11

Answer 1

The correct answer is B) 7

Answer 2

B) 7

Explanation:

A common factor among several numbers is when we break down each number into prime factors, and one or more prime factors are common for the set of numbers.

We express each term in prime factors and see which is a common factor for all numbers set

`21=3.7\\ 91=7.13\\154=2.7.11\\ 217=7.31\\ 315=3^2.5.7`

When we decompose them into prime factors, we observe that 7 is the common factor