Edexcel IGCSE Math A Higher 3.2 Function Notation Questions

Practise evaluating, composing and restricting functions, including inverse notation, excluded domain values and algebraic forms.

Exam points

[Maximum number: 4]

f is the function such that f(x)=4-3 x

(a)

Work out f(5)
g is the function such that $\mathrm{g}(x)=\frac{1}{1-2 x}$

[ 1 ]

(b)

Find the value of x that cannot be included in any domain of g

[ 1 ]

For $g(x)=\frac{1}{1-2x}$ , the denominator cannot be zero:
$1-2x\ne0$

Final answer:
$x\ne0.5$

(c)

Work out fg(-1.5)

[ 2 ]

$g(-1.5)=\frac{1}{1-2(-1.5)}=\frac14=0.25$ f(g(-1.5))=4-3(0.25)=3.25

Final answer:
3.25

[Maximum number: 1]

f is the function such that f(x)=4-3 x

Work out f(5)
g is the function such that $\mathrm{g}(x)=\frac{1}{1-2 x}$

[Maximum number: 1]

f is the function such that f(x)=4-3 x

Find the value of x that cannot be included in any domain of g

For $g(x)=\frac{1}{1-2x}$ , the denominator cannot be zero:
$1-2x\ne0$

Final answer:
$x\ne0.5$

[Maximum number: 2]

f is the function such that f(x)=4-3 x

Work out fg(-1.5)

$g(-1.5)=\frac{1}{1-2(-1.5)}=\frac14=0.25$ f(g(-1.5))=4-3(0.25)=3.25

Final answer:
3.25

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