Forming Expressions, Basic Rules of Algbera. How to Write Down Expressions.

In algebra, adding and taking are done exactly as they are. When multiplying put the number first followed by the letter (leave out the multiplication sign) and dividing can be written like a fraction (use a slash not a ÷).

So basically, adding and taking are written down normally, and it’s only multiplying and dividing which have to be written in a certain way.

Example 1

A fish pond contains an unknown amount of fish. Write down an a line of algebra for the amount of fish in the pond if:

a) 2 extra fish are added.

b) 2 fish are taken out of the pond.

c) the amount of fish in the pond is multiplied by 2.

d) the amount of fish in the pond is halved.

Answers

First call the original amount of fish in the pond f.

a) f + 2 (since adding is done exactly the same in algebra).

b) f – 2 (since taking is done exactly the same in algebra).

c) 2f (since we are multiplying the fish by 2 so put the number first followed by the letter).

d) f/2 (since divides are written as a fraction).

Example 2

A biscuit tin contains an unknown amount of biscuits. Write down an a line of algebra) for the amount of biscuits in the tin if:

a) 5 biscuits are added to the tin

b) 6 biscuits are taken out of the tin.

c) the amount of biscuits in the tin are multiplied by 7.

d) the amount of biscuits in the tin is divided by 8.

Answers

First call the original amount of biscuits in the tin b.

a) b + 5 (since adding is done exactly the same in algebra).

b) b – 6 (since taking is done exactly the same in algebra).

c) 7b (since we are multiplying the biscuits by 7 so put the number first followed by the letter).

d) b/8 (since divides are written as a fraction).

To go over some more worked examples on writing down expressions then click here.