Use Simple Formulae

Sometimes in Maths numbers can be replaced by letters but do not be put off by letters!

Letters are used for a special type of Maths, called algebra.

 

When we use algebra, we use 'formula'.

Formula is a concise, simple way of showing information with symbols.

 

There are lots of formulas in Maths to find.

For example: area, perimeter and circumference. 

 

Example 1:

 

If a = 6, b = 3 and c = 7, calculate the value of:

 

1. a + b =             2. a - b =            3. c + b - a = 

 

Solution:

 

1. a + b

    = 6 + 3 = 9 

 

2. a - b

   = 6 - 3 = 3

 

3. c + b - a

    = 7 + 3 - 6 = 4

 

Reminders:

 

There are some rules to remember when using formula:

We write:

 

2 x a as 2a

a x b = ab

a ÷ b as a/b

 

Example 2:

 

If p = 6, q = 12, r = 4 and s = 3 calculate the value of:

 

1. rs           2. 2r + 3s            3. s/3

 

Solution:

 

1. rs = r x s 

          = 4 x 3 = 12

 

2. 2r + 3s  = 2 x r + 3 x s

                 = 2 x 4 + 3 x 3 

                 =8 + 9 = 17

 

3. s/3 = 3 / 3 

          = 1