How do you evaluate log_6 (1/216)?

2 Answers
Sep 21, 2016

log_6 (1/216) =-3

Explanation:

Think of a log term asking a question.

log_10 100 can be read as..

"What index of 10 gives 100?"
"To what power must 10 be raised to equal 100?"

The answer is 2 because 10^2 = 100

log_10 100 = 2

It really is an advantage to know all the powers up to 1000.

Note that 6^3 = 216

Write the expression slightly differently as

log_6 (1/216) = log_6 (1/6^3) = log_6 6^-3

The answer is now obvious..

"What index of 6 will give 6^-3"?

"To what power must 6 be raised to equal 6^-3"?

log_6 (1/216) =-3

Sep 21, 2016

log_6 (1/216)=-3.

Explanation:

If log_6 (1/216)=x, "then, "6^x=1/216=1/6^3=6^-3......["by, Defn."]

rArr x=-3.

:. log_6 (1/216)=-3.