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Re: 3^7[(3^4+3^5)+(3^5+3^6)+(3^6+3^7)3^7] is what multiple of 17? [#permalink]
BrentGMATPrepNow wrote:
rheam25 wrote:
\(3^7[\)(\(3^{−4}\)+\(3^{−5}\))+(\(3^{−5}\)+\(3^{−6}\))+(\(3^{−6}\)+\(3^{−7}\)) –\(3^{−7}\) ] is what multiple of 17?

A) 1
B) 2
C) 3
D) 4
E) 11


Take: \(3^7[\)(\(3^{−4}\)+\(3^{−5}\))+(\(3^{−5}\)+\(3^{−6}\))+(\(3^{−6}\)+\(3^{−7}\)) –\(3^{−7}\) ]

Expand to get: \(3^3 + 3^2 + 3^2 + 3^1 + 3^1 + 1 - 1\)

Evaluate: \(27 + 9 + 9 + 3 + 3 + 1 - 1\)

Evaluate: \(51\)

Since \(51 = (3)(17)\), the correct answer is C

Cheers,
Brent

hi
In this question can you please explain this expansion? "Expand to get: \(3^3 + 3^2 + 3^2 + 3^1 + 3^1 + 1 - 1\)". I didn't understand it
GMAT Club Bot
Re: 3^7[(3^4+3^5)+(3^5+3^6)+(3^6+3^7)3^7] is what multiple of 17? [#permalink]
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