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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 'formulae'.
A formula is a concise, simple way of showing information with symbols.
There are lots of formulae 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
Answer
1. a + b = 6 + 3 = 9
2. a - b = 6 - 3 = 3
3. c + b - a = 7 + 3 - 6 = 4
There are some rules to remember when using formulae.
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
Answer
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
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Question
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