k = 2^n + 3, where n is an integer greater than 1. If k is divisible by 9, which of the following MUST be divisible by 9? Choose the correct choice from the following.
A) 2^n - 6 B) 2^n - 2 C) 2^n D) 2^n + 4 E) 2^n + 5
Given: k, M and N are integers   If k is a divisor of both N and M, then k is a divisor of N+M (and N–M and M–N)   We're told that 9 is a divisor of 2^n + 3   We also know that 9 is a divisor of9.   So, applying the above rule, 9 is a divisor of 2^n + 3 +9, and 9 is a divisor of 2^n + 3 -9= 2^n-6   2^n - 6
<result>A</result>
k = 2^n + 3, where n is an integer greater than 1. If k is divisible by 9, which of the following MUST be divisible by 9?