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Date November 2016 Marks available 2 Reference code 16N.1.SL.TZ0.S_1
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number S_1 Adapted from N/A

Question

Let f ( x ) = x 2 4 x + 5 .

The function can also be expressed in the form f ( x ) = ( x h ) 2 + k .

Find the equation of the axis of symmetry of the graph of f .

[2]
a.

(i)     Write down the value of h .

(ii)     Find the value of k .

[4]
b.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

correct approach     (A1)

eg  ( 4 ) 2 ,   f ( x ) = 2 x 4 = 0 ,  ( x 2 4 x + 4 ) + 5 4

x = 2  (must be an equation)     A1     N2

[2 marks]

a.

(i)     h = 2      A1     N1

(ii)     METHOD 1

valid attempt to find k     (M1)

eg f ( 2 )

correct substitution into their function     (A1)

eg ( 2 ) 2 4 ( 2 ) + 5

k = 1      A1     N2

METHOD 2

valid attempt to complete the square     (M1)

eg x 2 4 x + 4

correct working     (A1)

eg ( x 2 4 x + 4 ) 4 + 5 ,   ( x 2 ) 2 + 1

k = 1      A1     N2

[4 marks]

b.

Examiners report

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

Syllabus sections

Topic 2—Functions » SL 2.5—Modelling functions
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Topic 2—Functions

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