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Date May 2019 Marks available 6 Reference code 19M.1.AHL.TZ1.H_10
Level Additional Higher Level Paper Paper 1 Time zone Time zone 1
Command term Find Question number H_10 Adapted from N/A

Question

The function  p ( x ) is defined by p(x)=x33x2+8x24 where x R .

Find the remainder when p ( x ) is divided by  ( x 2 ) .

[2]
a.i.

Find the remainder when p ( x ) is divided by  ( x 3 ) .

[1]
a.ii.

Prove that  p ( x ) has only one real zero.

[4]
b.

Write down the transformation that will transform the graph of  y = p ( x ) onto the graph of y=8x312x2+16x24.

[2]
c.

The random variable X follows a Poisson distribution with a mean of λ and  6 P ( X = 3 ) = 3 P ( X = 2 ) 2 P ( X = 1 ) + 3 P ( X = 0 ) .

Find the value of  λ .

[6]
d.

Markscheme

p ( 2 ) = 8 12 + 16 24        (M1)

Note: Award M1 for a valid attempt at remainder theorem or polynomial division.

= −12     A1

remainder = −12

[2 marks]

a.i.

p ( 3 ) = 27 27 + 24 24 = 0      A1 

remainder = 0

[1 mark]

a.ii.

x = 3 (is a zero)     A1

Note: Can be seen anywhere.

EITHER

factorise to get  ( x 3 ) ( x 2 + 8 )       (M1)A1

x 2 + 8 0 (for  x R ) (or equivalent statement)      R1

Note: Award R1 if correct two complex roots are given.

OR

p ( x ) = 3 x 2 6 x + 8    A1

attempting to show  p ( x ) 0        M1

eg discriminant = 36 – 96 < 0, completing the square

no turning points       R1

THEN

only one real zero (as the curve is continuous)      AG

[4 marks]

b.

new graph is  y = p ( 2 x )      (M1)

stretch parallel to the x -axis (with x = 0 invariant), scale factor 0.5    A1

Note: Accept “horizontal” instead of “parallel to the x -axis”.

[2 marks]

c.

6 λ 3 e λ 6 = 3 λ 2 e λ 2 2 λ e λ + 3 e λ      M1A1

Note: Allow factorials in the denominator for A1.

2 λ 3 3 λ 2 + 4 λ 6 = 0     A1

Note: Accept any correct cubic equation without factorials and e λ .

EITHER

4 ( 2 λ 3 3 λ 2 + 4 λ 6 ) = 8 λ 3 12 λ 2 + 16 λ 24 = 0        (M1)

2 λ = 3       (A1)

OR

( 2 λ 3 ) ( λ 2 + 2 ) = 0        (M1)(A1)

THEN

λ = 1.5    A1

[6 marks]

d.

Examiners report

[N/A]
a.i.
[N/A]
a.ii.
[N/A]
b.
[N/A]
c.
[N/A]
d.

Syllabus sections

Topic 4—Statistics and probability » SL 4.8—Binomial distribution
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Topic 2—Functions » AHL 2.8—Transformations of graphs, composite transformations
Topic 4—Statistics and probability » AHL 4.17—Poisson distribution
Topic 2—Functions
Topic 4—Statistics and probability

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