# Edexcel maths revision notes

This is everything i didn't understand in edexcel maths. Hope it helps!

- Created by: Alex Broadway
- Created on: 10-06-13 13:42

First 284 words of the document:

HCF AND LCM

LCM:

1. Write out the prime factors of both numbers

2. Cross out 1 of each repeat

3. Times the remaining numbers together

HCF:

1. Write out the prime factors

2. Times one of each repeat together.

PRIME FACTOR DECOMPOSITION

1. Do a factor tree

2. Write the end of each branch as a list of numbers times together.

NB: Put repeats into powers eg 2*2*3 = 2 squared *3

INDEX LAWS FOR FRACTIONAL, INTEGER AND NEGATIVE POWERS

Anything to the power of a negative is 1 divided by the number to the original power

Anything to the power of a fraction is the root of the number

CONVERT BETWEEN RECURRING DECIMALS AND FRACTIONS

1. Times the decimal by a power of 10 to make the repeating number(s) to the left of the

decimal point.

2. This is 10x.

3. Take 1x away from 10x to get 9x(which should be an integer)

4. Divide this number by 9 to get a fraction.

COMPOUND INTEREST

1. Write down the interest and the number of years.

2. Times the initial money by the interest to the power of the number of years.

3. If reverse, times by the root of the number of years.

REPEATED PROPORTIONAL CHANGE

The same as compound interest

RECIPROCAL AND INVERSE CALCULATION

Reciprocal: 1 over

Inverse: opposite

SURDS AND PI

Rationalising the denominator:

If just a surd on the bottom times by a fraction with that surd on the top and bottom

If an expression(4+root3) times by a fraction with the expression on top and bottom but

reverse the sign in the middle.

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