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Date May Specimen paper Marks available 2 Reference code SPM.1.SL.TZ0.5
Level Standard Level Paper Paper 1 (without calculator) Time zone Time zone 0
Command term Show that Question number 5 Adapted from N/A

Question

The functions f and g are defined such that f(x)=x+34 and g(x)=8x+5.

Show that (gf)(x)=2x+11.

[2]
a.

Given that (gf)1(a)=4, find the value of a.

[3]
b.

Markscheme

attempt to form composition       M1

correct substitution g(x+34)=8(x+34)+5    A1

(gf)(x)=2x+11     AG

[2 marks]

a.

attempt to substitute 4 (seen anywhere)     (M1)

correct equation a=2×4+11      (A1)

a = 19     A1

[3 marks]

b.

Examiners report

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

Syllabus sections

Topic 2—Functions » SL 2.5—Composite functions, identity, finding inverse
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Topic 2—Functions

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