Page 20 - MAT KS3 Y8 Cambridge CheckPoint

2 Sequences, expressions and formulae

A formula is a set of instructions for working something out. It is a Key words
e
y word
K
s
rule that can be written as letters or in words. The plural of formula
is formulae. Make sure you learn and
understand these key words:
People use formulae in everyday life to work out all sorts of things.
linear sequence
An employer may use a formula to work out how much to pay the
people who work for them. term-to-term rule
position-to-term rule
They could use a formula such as P = R × H, where P is the pay, R is nth term
the amount paid per hour and H is the number of hours worked.
function
function machine
input
output
mapping diagram
map
algebraically
equation
expression
variable
linear expression
formula (formulae)
derive

Engineers may use a formula to work out the time it takes
for a car to accelerate from one speed to another.
−
They could use the formula t = vu , where t is the time,
a
v is the finishing speed, u is the starting speed and a is the
acceleration.
Doctors may use a formula to work out how healthy a person
is. They could use the formula for finding the person’s body
mass index (BMI).
The formula is: BMI = mass , where the person’s mass is
height 2
measured in kilograms and their height is measured in metres.
If a person’s BMI is too high or too low the doctor may ask them to
lose some weight, or put some on, to make them healthier.
In this unit you will learn how to substitute numbers into formulae
and expressions. You will also learn more about number sequences
and functions.

18 2 Sequences, expressions and formulae