What is the largest prime factor of 27^3−9^3−3^6?
Pick:
A) 2
B) 3
C) 5
D) 7
E) 11
27^3−9^3−3^6 = 3^9 - 3^6 - 3^6 = 3^6( 3^3-1-1) = 3^6 (27-2) = 3^6 * 5^2.   Two prime factors are 3 and 5. Therefore, max prime factor is 5.   ANSWER:5
<result>C</result>
What is the largest prime factor of 27^3−9^3−3^6?