We often use formulae without even noticing. For example, we might convert miles to km by multiplying by 1.6, or find the circumference of a circle by multiplying pi by the diameter.
km = 1.6 x miles is an example of a formula.
We have already seen that km = 1.6 x miles and C = π × d are examples of formulae. There are many others that we use regularly in other subjects. Sometimes we have to construct our own formula:
A taxi firm charges £0.50 per mile plus a fixed charge of £2.00. Write down a formula for the cost (C) of hiring this taxi to travel 'n' miles.
So travelling for 'n' miles will cost £2 + n x £0.50.
The formula is C = £2 + (n x £0.50).
Note: £0.50 = 50p.
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