# Logarithms - Product Rule

These lessons, with videos, examples, solutions and worksheets help Algebra students learn about the product rule in logarithms.

The following table gives the logarithm rules. Scroll down the page for examples and solutions for the Product Rule.

What is the Product Rule of Logarithms?
The log of a product is equal to the sum of the logs of its factors.
logb(xy) = logbx + logby

There are a few rules that can be used when solving logarithmic equations. One of these rules is the logarithmic product rule, which can be used to separate complex logs into multiple terms. Other rules that can be useful are the quotient rule and the power rule of logarithms. The logarithmic product rule is important and is used often in calculus when manipulating logs and simplifying terms for derivation.

How to use the product rule for logarithms?
logb(xy) = logbx + logby
Do not be confused: logb(x + y) ≠ logbx + logby

How to expand Logarithms using the Product Rule for Logs?

Examples:
Use the product rule for logarithms to rewrite the logarithm of a product as the sum of logarithms of its factors.

1. logb(2xyz)
2. log2(15x(7x + 2))

Logarithms - Product Rule of Logs

Examples:
logb(xy)
logb(z2y)
log381
logb(x2 - 4)

Expand Logarithmic Expressions

Examples:
Expand each logarithm as much as possible.

1. log2(x4√x5)
2. ln(x3y2/z5)

More examples on how to expand logarithms.

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