does anyone know how to get to the right answer 7?

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thanks.

What is the greatest prime factor of 4^17 - 2^28?

2
3
5
7
11

OA is 7.

I figured out the right answer and what I was doing wrong.

In order to solve this:

get everything in the same base

(2^2)^17 - 2^28
2^34 - 2^28
2^28 (2^6 -1)
2^28 (64-1)
2^28 * 63

the factors of 63 is 9 *7

7 is the biggest prime

(originally, I just subtract 28 from 34, but that is WRONG)

well played.

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