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IMO A

6^15 = (3*2)^15 = 3^15 * 2^15 = a * b^c

1) a is not divisible be 3, which implies that b^c = 3^15 ==> c= 15

2) bis a prime number, but in the equation we can deduce from 3^15 * 2^15 = a * b^c that so is a and hence not enough

Answer A
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Bunuel
If a, b and c are integers greater than one, and \(6^{15}=a*b^c\), what is the value of c?

(1) a is not divisible by 3.
(2) b is prime.


\(6^{15}=a*b^c…2^{15}3^{15}=ab^c\)

(1) a is not divisible by 3. insufic

\(2^{15}3^{15}=ab^c…a=2^{something}…b=(2•3)^{something}…b=3^{something}\)
\(a=2^3…b^c=2^{12}3^15=(2^43^5)^3\)
\(a=2^5…b^c=2^{10}3^15=(2^23^3)^5\)
\(a=2^{15}…b^c=3^{15}\)

(2) b is prime. insufic

\(b^c=3^{something}…b^c=2^{something}\)

(1&2) sufic

\(a=2^{15}…b^c=3^{15}…c=15\)

Ans (C)
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