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nisha.menon294
- Senior | Next Rank: 100 Posts
- Posts: 44
- Joined: Sat Apr 10, 2010 8:33 am
nisha.menon294 wrote:What is the greatest prime factor of 4^17-2^28
a)2
b)3
c)5
d)7
e)11
OA is D
the question can be re-written as : 2^34 - 2^28
= 2^28 (2^6-1)
= 2^28 * 63
=2^28 * 3^2 * 7
Hence, greatest of 2,3, and 7 will be option D.
