Year 11 - Maths
Writing composite functions
Functions and proof
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Year 11 - Maths
Functions and proof
In this unit pupils will further develop their understanding of algebraic notation and graphs by learning about functions, their inverses and composite functions.
You will learn to write a composite function both numerically and algebraically.
Using function notation, you can write a composite function. Function notation can be replaced with the algebraic form.
The composite function gf($$x$$) is the combination of f($$x$$) and g($$x$$). The output from f($$x$$) is the input for g($$x$$). Use this word when showing your method, then check your final answer is reasonable.
Mistake: Pupils may try to evaluate composite functions by working from left to right. Correction: Remind pupils that they cannot do this as each function needs an input and with composite functions the input needs to be evaluated before it can be used.
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