This is a question from a GMAT Prep test I just took ...
What is the greatest prime factor of 4^17 - 2^28?
Answers:
2
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11
7
Prime Factorization
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If u take the common factor 2^28 u will get a 1 inside bracesquick question..why did you subtract 1 from the 64? I am trying to figure this one out and Im still kind of confused. Thanks
2^34 - 2 ^ 28
= 2^28 ( 2 ^ 6 - 1) (which = 2^28*2^6 - 2^28*1 = 2^34 - 2^28)
Hope this helps!
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CMoore wrote:quick question..why did you subtract 1 from the 64? I am trying to figure this one out and Im still kind of confused. Thanks
A^n - A^m = A^(n-m). hope this helps. Property of powers. (ALGEBRA)
Am I missing something here? A^n - A^m does NOT = A^(n-m). That's why you factor out. e.g. 2^4 - 2^2 doesn't = 2^2. It's 2^2 (2^2 - 1) = 4 (3) = 12.vish150783 wrote:CMoore wrote:quick question..why did you subtract 1 from the 64? I am trying to figure this one out and Im still kind of confused. Thanks
A^n - A^m = A^(n-m). hope this helps. Property of powers. (ALGEBRA)