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BryanBTGMAT
- Newbie | Next Rank: 10 Posts
- Posts: 5
- Joined: Wed Sep 12, 2012 7:00 pm
Can someone explain the ruled used on the bold line? I do not recall how this factoring works. Thank you!
4^17 - 2^28
Understood = (2²)^17 - 2^28
Understood = 2^34 - 2^28
Do not understand the factoring here= 2^28(2^6 - 1)
Understood = 2^28(63)
Understood = 2^28(7 * 3^2)
Therefore, the greatest prime factor of 4^17 - 2^28 is 7.
The correct answer is D.
4^17 - 2^28
Understood = (2²)^17 - 2^28
Understood = 2^34 - 2^28
Do not understand the factoring here= 2^28(2^6 - 1)
Understood = 2^28(63)
Understood = 2^28(7 * 3^2)
Therefore, the greatest prime factor of 4^17 - 2^28 is 7.
The correct answer is D.
