# Edexel Maths Unit 3

All of the stuff for Edexel Maths Unit 3

HideShow resource information
• Created by: Charlotte
• Created on: 02-06-12 11:29

1 of 18

2 of 18

3 of 18

## Heregoes...Standard Index Form

Standard Index Form can be used to write very small or very big numbers.

A × 10 n

• "A" is always between 1 and 10
• "N" is the number of decimal places moved
• If its a small nimber, the power is a minus, its stays normal if it is a big number

eg.

• 920 000 = 9.2 X 10 5
• 0.007 03 = 7.03 X 10 -3
4 of 18

## Proportion (Direct)

Direct Proportion: y = kx

Both increase together

5 of 18

## Proportion (Inverse)

Inverse Proportion: y = k/x

One increases and the other decreases

6 of 18

## Proportion (Inverse Square Variation)

You can have all sorts of relationships between x and y, like y = kx2 or y = kx3 etc. The most important type is y = kx2 and is called inverse square variation.

lol. a square watermelon.

7 of 18

## Percentage (Calculate the Original amount of Perce

Most people get these wrong. Dont be one of those people or you'll fail the exam.

EXAMPLE: A hampster increases in value by 20% to £72 000. Find out what it was worth before the rise.

METHOD:

• £72 000 = 120%
• Divide by 120 - £600 = 1%
• Times by 100 - £60 000 = 100%, so the original price was £60 000

8 of 18

## Repeated Proportional Change Problems

EXAMPLE: Charlotte buys a massive  jar of paint for £800. The Paint loses a quarter of its value each year. Find the Value of the paint after 3 years.

• Value after 1 year is: £800 X 0.75 = £600
• Value after 2 years is: £600 X 0.75 = £450
• Value after 3 years is: £450 X 0.75 = £337.50

9 of 18

10 of 18

11 of 18

12 of 18

13 of 18

## Bounds

Maximum and Minimum Values for Calculations - When a calculation is done using rounded off values, there will be some discrepency between the calculated value and the Acual value.

Upper and Lower Bounds of a Measurement - THE SIMPLE RULE: The real value can be as much as half the rounded unit abouve and below the rounded off value.

14 of 18

## Example of Bounds

A garden is measured as being 5.3 m X 4.2 m to the nearest 10 cm. This gives an area of 22.26m2, but this is not the actual floor area because the real values could be anything from 5.25 and 5.35 and 4.15 and 4.25.

• The maximum possible garden area : 5.35 X 4.25 = 22.7375 m2
• The minimum possible garden area: 5.25 X 4.15 = 21.7875 m2

15 of 18

## The Four Main Facts of Reciprocals

• The reciprocal of a number is 'one over' the number eg. the reciprocal of 5 is 1/5
• You can find the reciprocal of a fraction by turing it upside down eg. the reciprocal of 3/8  = 8/3
• A nuber multipled by its reciprocal gives 1. eg. 6/7 X 7/6 = 1
• 0 has no reciprocal because you cant divide anything by 0
16 of 18

17 of 18

## Solving Equations

• Get rid of any square root signs by squaring both sides
• Get every thing off of the bottom by cross multiplying up to every other term
• Multiply out brackets
• Collect all subject terms on one side of the = and all non-subject terms on the other. Remember to reverse the + / - sign of any term that crosses the =
• Combine together like terms on each side of the equation, and reduce it to the form ax = b, where A and B are just numbers (or bunches of letters)
• Slide a underneath b to give x = b/a, divide and thats the answer
18 of 18

## Similar Mathematics resources:

See all Mathematics resources »