What is the greatest prime factor of 4^17 - 2^28
a)2
B) 3
C) 5
D) 7
E) 11
Clearly, I'm missing something. Why is it not A
OA - D
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Greatest prime factor
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gaggleofgirls
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Because 2^34 - s^28 does not = 2^6
2^34/2^28 = 2^6
So, we need to figure out something useful to do with 2^34 - 2^28
Factor out 2^28 and you get:
2^28 (2^6-1) =
2^28 (63)
2^28 has a whole bunh of 2s as its factors, but 63 is 7 * 3 * 3,
So the greatest prime factor of 2^28(63) = 7.
Answer = D.
-Carrie
2^34/2^28 = 2^6
So, we need to figure out something useful to do with 2^34 - 2^28
Factor out 2^28 and you get:
2^28 (2^6-1) =
2^28 (63)
2^28 has a whole bunh of 2s as its factors, but 63 is 7 * 3 * 3,
So the greatest prime factor of 2^28(63) = 7.
Answer = D.
-Carrie
