Laws of logarithmsIB SL/HL

Logarithms

Logarithms were invented by John Napier as another form of writing indices.

The rules of logarithms

1. Use your calculator to find:

From your answers suggest a simplification for log a + log b

2. Use your calculator to find:

From your answers suggest a simplification for log a - log b

3. Use your calculator to find:

From your answers suggest a simplification for nlog a

Change of base rule

Start with x=

Write as an index

Take a log of both sides

Use the power rule

Leave x on it’s own.

The Laws of Logarithms