How_To_Be_Good_At_Math

Add the numbers within the

brackets, then multiply the

answer by 5

ALGEBRA • EQUATIONS 303

20

=

=

(a + b) + c a + (b + c) a (b + c) = ab + ac

(3 + 4) + 6 3 + (4 + 6)

Add the numbers within the

brackets, then add 6 to get 13

Multiply the numbers

within the brackets,

then add the answers

b

WRITING EQUATIONS WITH ALGEBRA

In algebra, we use some special words and phrases. We also write

equations slightly differently compared with when we’re using numbers.

In algebra, a number that we do not know yet can

be represented by a letter. This is called a variable.

4ab

4 + c

Instead of writing a × b, we simply write ab. We leave

out the multiplication sign because it looks too much

like the letter x.

When we multiply numbers and letters, we write

the number first.

A number, a letter, or a combination of both is

called a term.

Two or more terms separated by a maths sign is

called an expression.

2b

ab

The distributive law

This is a law about multiplication. It says that

adding a group of numbers together and then

multiplying them by another number is the same as

doing each multiplication separately and then adding

them. Here’s an example of how this law works.

The associative law

Remember, brackets tell us which part of a

calculation to do first. This law tells us that when

we’re adding or multiplying, it doesn’t matter

where we put the brackets – the answer won’t

change. Take a look at this addition calculation.

5 × (2 + 4) = (5 × 2) + (5 × 4)

WRITING WITH NUMBERS WRITING WITH NUMBERS

WRITING WITH ALGEBRA WRITING WITH ALGEBRA

302-303-Algebra-Equations.indd 303 29/02/2016 18:07