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mathematicsprinted 49 · PDF 50
165 pagesrevision 46935
printed 49 · PDF 50
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If you are putting a number into fg(x)
STEP 1
Put the number into g(x)
STEP 2
Put the output of g(x) into f(x)
If you are using algebra, to find an expression for a composite function
STEP 1
For fg(x) put g(x) wherever you see x in f(x)
STEP 2
Simplify if necessary
An inverse function does the exact opposite of the function it came from
For example, if the function “doubles the number and adds 1” then its inverse is
“subtract 1 and halve the result”
It is the inverse operations in the reverse order
How do I write inverse functions?
An inverse function f-1 can be written as F-1 (x)
How do I find an inverse function?
The easiest way to find an inverse function is to 'cheat' and swap the x and y
variables
Note that this is a useful method but you MUST remember not to do this in any other
circumstances in maths
STEP 1
Write the function in the form y=..
STEP 2
Swap the Xs and Ys to get x =
STEP 3
Rearrange the expression to make y the subject again
STEP 4
Write as f-1(x) = … (or f-1 : x ↦ …)