Example

Try It 10.42: Evaluating log981\log_9 81, log82\log_8 2, and log319\log_3 \frac{1}{9}

To find the exact values of log981\log_9 81, log82\log_8 2, and log319\log_3 \frac{1}{9} without a calculator, rewrite each as an exponential equation by setting them equal to xx. For log981\log_9 81, the equation 9x=819^x = 81 simplifies to 9x=929^x = 9^2, meaning x=2x = 2. For log82\log_8 2, the equation 8x=28^x = 2 can be solved by recognizing that the cube root of 88 is 22, which corresponds to the exponent 13\frac{1}{3}, so x=13x = \frac{1}{3}. For log319\log_3 \frac{1}{9}, the equation 3x=193^x = \frac{1}{9} translates to 3x=323^x = 3^{-2}, yielding x=2x = -2.

0

1

Updated 2026-05-26

Contributors are:

Who are from:

Tags

OpenStax

Intermediate Algebra @ OpenStax

Ch.10 Exponential and Logarithmic Functions - Intermediate Algebra @ OpenStax

Algebra