algebra
posted by molly .
evaluate 15^(2log base15(9))

15^(log_{15}n) = n
That's the definition of the logarithm. It's the power of the base needed to get the number.
So, 15^log9 = 9 (using base 15)
15^2log9 = (15^log9)^2 = 9^2 = 81
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