IGCSE / Functions
Function, is an expression, rule, or law that defines a relationship between one variable
(the independent variable) and another variable (the dependent variable).
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For example:
f(x) = 3x + 1
Here is a function called f, such that x is mapped to 3x + 1
It is like the function machine concept that you learned in year 7.
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There are different ways to show it.
f: x -> 3x + 1 or f(x) = 3x + 1
but they mean the same thing, so don’t be scared.
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Input different values of x into the function; f(x) = 3x + 1,
we will obtain the corresponding values of y.
Domain and Range
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They are very important in this topic that you must know.
In simple form: Domain = x (the input), Range = y (the output)
Composite Functions
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Many students find it confusing, but they often given in the IGCSE exam and could carry up to 7 - 8 marks!
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Let me show you some examples:
Here is an example of a harder Composite Functions:
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Example 3:
Functions is one of the topics that always pop up in IGCSE exams and it is important to have a thorough understanding of the topic if you want to aim for a A* / 9.