Solving Logarithmic Equations

Solving Logarithmic Equations

Example

Question

Solve for \(p\):

\[18 \log{p} - 36 = 0\]

Make \(\log p\) the subject of the equation

\begin{align*} 18 \log{p} - 36 &= 0 \\ 18 \log{p} &= 36 \\ \cfrac{18 \log{p}}{18} &= \cfrac{36}{18} \\ \therefore \log{p} &= 2 \end{align*}

Change from logarithmic form to exponential form

\begin{align*} \log{p} &= 2 \\ \therefore p &= 10^{2} \\ &= 100 \end{align*}

Write the final answer

\(p = 100\)

Example

Question

Solve for \(n\) (correct to the nearest integer):

\[(\text{1.02})^{n} = 2\]

Change from exponential form to logarithmic form

\begin{align*} (\text{1.02})^{n} &= 2 \\ \therefore n &= \log_{\text{1.02}}{2} \end{align*}

Use a change of base to solve for \(n\)

\begin{align*} n &= \cfrac{\log{2}}{\log{\text{1.02}}} \\ \therefore n &= \text{35.00} \ldots \end{align*}

Write the final answer

\(n = 35\)

This lesson is part of:

Functions III

View Full Tutorial

Track Your Learning Progress

Sign in to unlock unlimited practice exams, tutorial practice quizzes, personalized weak area practice, AI study assistance with Lexi, and detailed performance analytics.