What is the greatest prime factor of \(3^6 - 1?\)
A. 2
B. 3
C. 7
D. 13
E. 17
Answer: D
Source: Manhattan GMAT
What is the greatest prime factor of \(3^6 - 1?\)
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Solution:Gmat_mission wrote: ↑Tue Nov 10, 2020 7:53 amWhat is the greatest prime factor of \(3^6 - 1?\)
A. 2
B. 3
C. 7
D. 13
E. 17
Answer: D
Since 3^6 - 1 = (3^3 + 1)(3^3 - 1) = 28 x 26 = 2^2 x 7 x 2 x 13, we see that its largest prime factor is 13.
Answer: D
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