How do you calculate log_5 7.2 with a calculator?

1 Answer
Gió
Aug 9, 2016

I found: 1.22656

Explanation:

Normally in a calculator you have two types of logs: one in base e and the other in base 10.
Our log is in base 5 but it isn't a problem because we can change base using the relationship:

log_a(x)=(log_(10)x)/(log_(10)a)

where we used the new base 10 that can be evaluated.

In our case we get:

log_5(7.2)=(log_(10)(7.2))/(log_(10)(5))=1.22656

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