Page 99 - Cambridge Checkpoint Mathematics Coursebook 7_Slide 02

9 Expressions and equations

An equation contains letters and numbers and it must have an Key words
equals sign.

An expression can contain numbers and letters, but it does not Make sure you learn and
understand these key words:
have an equals sign.
For example, 3x + 2 = 8 is an equation, whereas 3x + 2 is an expression. equation
expression
Th e equals sign, =, that we use today, was invented by a like terms
mathematician called Robert Recorde. simplify
collecting like terms
brackets
expand
solve
inverse operations
solution
change side, change sign

SCOTLAND
North Sea
Glasgow
NORTHERN Edinburgh
IRELAND UNITED KINGDOM
Londonderry Newcastle
Robert Recorde. Belfast
Isle of
Man Leeds
Robert Recorde was born in Tenby in Pembrokeshire in Dublin Irish Sea Liverpool Manchester
Sheffield
1510. He studied medicine at university and went on to IRELAND Nottingham
work as a doctor. Birmingham ENGLAND
WALES
Th roughout his life he wrote many mathematical Cardiff Bristol London
textbooks in the order in which he thought they should Southampton 0 50 100 m
be studied. He wrote all these books in English, instead Tenby, Pembrokeshire 0 FRANCE
100 km
50
of Latin or Greek, as he wanted them to be available to
everyone. He also used clear and
simple expressions to try to make them easy to follow.
In 1557 he wrote Th e Whetstone of Witte and it is in this
book that he used the modern equals sign (=) for the
fi rst time. Other mathematicians were using the letters
ae or oe or two vertical lines , ||, to mean equals.
Today Tenby is a bustling holiday town on the coast of
West Wales. Little do the holidaymakers know, while
they enjoy an ice cream on the beach, that they are in
the place where the inventor of the equals sign was born!
In this unit you will learn more about expressions and
equations, and how to solve them. Tenby Harbour.

9 Expressions and equations 97