# Logarithms Revision Notes for Core 2

Notes I created for logarithms. It is not to bad when you get your head around the laws of log etc, and should soon become easy marks in a C2 paper :)

- Created by: George
- Created on: 12-05-11 18:20

First 191 words of the document:

Mathematics Core 2 Logarithms

How to write an expression as a logarithm

Log a n = x could be written in the form a x = n, where a is called the base of the logarithm.

This is key for answering many log questions!

Laws of logarithms

If log a x = b and log a y = c

a b= x and a c = y (using the law from above)

Multiplication Law

xy = a b x a c = a b + c

log a xy = b + c (using the rule from above `how to write an expression as a logarithm)

log a xy = log a x + log a y

Division law

x / y = a b / a c = a b c

log a (x / y) = b c

log a (x / y) = log a x log a y

Power law

If we let x = log a y

Writing in other form: a x = y

Raise each side to the power z: (a x) z = y p

Writing back into logarithm form: log a y p = x z

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