At what rate of interest does it take six years of compounding monthly for an account to double in value?
How do you get from,
(1+r/12)^72=2 to
r= 12(2^(1/72)-1)
i really don't get what you needed.. but if you are just solving for in , then that is just simple algebra(and i think, there was a mistake in your grouping..)..
first, get the 72nd root of both sides, you will have
then multiply 12 to both sides,
lastly, subtract 1 to both sides,
now, is that what you want?