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Topic: [Solved] X as the exponent (Read 4147 times) previous topic - next topic

westfw

JimboZA had it right way back in the first reply.
Quote
Take logs of both sides, take the exponent to the front, solve for exponent

See "rule 4" here: http://www.mathwords.com/l/logarithm_rules.htm

5 ^ X = 18
log(5^x) = log(18)
x * log(5) = log(18)
x = log(18)/log(5)

Or you can think:
5^x = 18
logbase5(5^x) = logbase518
x = logbase518
and then use the "change of base" forumla (rule 5 at the above page.)

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