freeCodeCamp/guide/english/mathematics/basic-log-rules-and-expandi.../index.md

1.8 KiB

title
Basic Log Rules and Expanding Log Expressions

Basic Log Rules and Expanding Log Expressions

The following are commonly used basic log rules:

Logarithm Product Rule

logb (x * y) = logb (x) + logb (y)

Logarithm Quotient Rule

logb (x / y) = logb (x) - logb (y)

Logarithm Power Rule

logb (xy) = y * logb (x)

Logarithm of Negative Number

logb (x) is undefined when x < 0

Logarithm of 0

logb (0) is undefined

limx → 0+ logb (x) = -infinity

Logarithm of 1

logb (1) = 0

Logarithm of the Base

logb (b) = 1

Logarithm of Infinity

lim x → infinity logb (x) = infinity

Logarithm Base Switch Rule

logb (c) = 1 / logc (b)

Logarithm Base Change Rule

logb (x) = logc (x) / logc (b)

More Information:

Logarithm Rules