### GCSE Maths Revison ; Factors

#### 2nd May 2014

We like to remember with BODMAS: If there are no brackets, we need to work out what part of the formula to calculate first. To know what to work out first we use the BODMAS rule. BODMAS stands for:

Brackets, Of, Division, Multiplication, Addition, Subtraction.

We must do things in that order.

Expansion: Brackets can also be used to keep terms together or to factorise.

Expansion normally means the same thing as to multiply out. For example 4(X + 4) would be expanded to 4X + 16.

Factors: The factors of a whole number are the numbers that will divide into it an exact amount of times. The factors of 12 are 1, 2, 3, 4, 6 & 12. The factors of 20 are 1, 2, 4, 5, 10 & 20.

Factorisation in algebra:  You may need to be able to factorise a basic expression in algebra. Look at the formula A = πr2 + πd we can see that on the right, both terms contain π, so this can be re-written as A = π(r2 + d).

So: P = 2l + 2b can be factorised to  P = 2(l + b)

D = πr – r3 can be factorised to D = r(π – r2 )

Check your answers by multiplying out the brackets again to check whether you’ve got the same as you started with.

Simplification: Does exactly as it says, it what you can do to make an expression more simple.

Example: to simplify r = 3(X + y) + 4(2X + y), you need to expand both brackets to give

r = 3X + 3y + 8X + 4y, which will then simplify to r = 11X + 7y by combining the similar terms.

More difficult example:

(4X + 2) (4X + 6) = 16X2 + 24X + 8X + 12

= 16X2 + 32X + 12

For more maths jams, follow the link here where you can access free demo's http://learnthrumusic.co.uk/subjects/#subject-2

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