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Date May 2018 Marks available 2 Reference code 18M.1.sl.TZ1.1
Level SL only Paper 1 Time zone TZ1
Command term Find Question number 1 Adapted from N/A

Question

Let \(f\left( x \right) = \sqrt {x + 2} \) for x ≥ 2 and g(x) = 3x − 7 for \(x \in \mathbb{R}\).

Write down f (14).

[1]
a.

Find \(\left( {g \circ f} \right)\) (14).

[2]
b.

Find g−1(x).

[3]
c.

Markscheme

f (14) = 4     A1 N1

[1 mark]

a.

attempt to substitute     (M1)

eg   g (4), 3 × 4 − 7

5     A1 N2

[2 marks]

b.

interchanging x and y (seen anywhere)     (M1)

eg   x = 3y − 7

evidence of correct manipulation     (A1)

eg   x + 7 = 3y

\({g^{ - 1}}\left( x \right) = \frac{{x + 7}}{3}\)     A1 N3

[3 marks]

 

 

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Topic 2 - Functions and equations » 2.1 » Concept of function \(f:x \mapsto f\left( x \right)\) .
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