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Date November 2017 Marks available 4 Reference code 17N.1.AHL.TZ0.H_6
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Sketch Question number H_6 Adapted from N/A

Question

Sketch the graph of y = 1 3 x x 2 , showing clearly any asymptotes and stating the coordinates of any points of intersection with the axes.

N17/5/MATHL/HP1/ENG/TZ0/06.a

[4]
a.

Hence or otherwise, solve the inequality | 1 3 x x 2 | < 2 .

[5]
b.

Markscheme

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

N17/5/MATHL/HP1/ENG/TZ0/06.a/M

correct vertical asymptote     A1

shape including correct horizontal asymptote     A1

( 1 3 ,   0 )     A1

( 0 ,   1 2 )     A1

 

Note:     Accept x = 1 3 and y = 1 2 marked on the axes.

 

[4 marks]

a.

METHOD 1

N17/5/MATHL/HP1/ENG/TZ0/06.b/M

1 3 x x 2 = 2     (M1)

x = 1    A1

( 1 3 x x 2 ) = 2     (M1)

 

Note:     Award this M1 for the line above or a correct sketch identifying a second critical value.

 

x = 3     A1

solution is 3 < x < 1     A1

 

METHOD 2

| 1 3 x | < 2 | x 2 | ,   x 2

1 6 x + 9 x 2 < 4 ( x 2 4 x + 4 )     (M1)A1

1 6 x + 9 x 2 < 4 x 2 16 x + 16

5 x 2 + 10 x 15 < 0

x 2 + 2 x 3 < 0     A1

( x + 3 ) ( x 1 ) < 0     (M1)

solution is 3 < x < 1     A1

 

METHOD 3

2 < 1 3 x x 2 < 2

consider 1 3 x x 2 < 2     (M1)

 

Note:     Also allow consideration of “>” or “=” for the awarding of the M mark.

 

recognition of critical value at x = 1     A1

consider 2 < 1 3 x x 2     (M1)

 

Note:     Also allow consideration of “>” or “=” for the awarding of the M mark.

 

recognition of critical value at x = 3     A1

solution is 3 < x < 1     A1

[5 marks]

 

b.

Examiners report

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

Syllabus sections

Topic 2—Functions » SL 2.2—Functions, notation domain, range and inverse as reflection
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