Which of the following numbers is a divisor of (49¹⁵?

Question: Which of the following numbers is a divisor of (49¹⁵ - 1)?

Solution:
aⁿ - bⁿ is divisible by (a + b) when n is an even positive integer.
Here, a & b should be prime number.

(49¹⁵ - 1)
⇒ {(7²)¹⁵ - 1)
⇒ (7³⁰ - 1)
Here, 30 is a positive integer.
According to the concept, (7³⁰ - 1) is divisible by (7 + 1) i.e., 8.
∴ 8 is a divisor of (49¹⁵ - 1).