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Date May 2018 Marks available 5 Reference code 18M.2.AHL.TZ2.H_2
Level Additional Higher Level Paper Paper 2 Time zone Time zone 2
Command term Find Question number H_2 Adapted from N/A

Question

The polynomial  x 4 + p x 3 + q x 2 + r x + 6  is exactly divisible by each of  ( x 1 ) ( x 2 ) and  ( x 3 ) .

Find the values of  p q and  r .

Markscheme

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

METHOD 1

substitute each of  x = 1,2 and 3 into the quartic and equate to zero      (M1)

p + q + r = 7

4 p + 2 q + r = 11  or equivalent        (A2)

9 p + 3 q + r = 29

Note: Award A2 for all three equations correct, A1 for two correct.

attempting to solve the system of equations      (M1)

p = −7,  q = 17,  r = −17     A1

Note: Only award M1 when some numerical values are found when solving algebraically or using GDC.

 

METHOD 2

attempt to find fourth factor      (M1)

( x 1 )      A1

attempt to expand  ( x 1 ) 2 ( x 2 ) ( x 3 )      M1

x 4 7 x 3 + 17 x 2 17 x + 6 ( p = −7,  q = 17,  r = −17)     A2

Note: Award A2 for all three values correct, A1 for two correct.

Note: Accept long / synthetic division.

[5 marks]

Examiners report

[N/A]

Syllabus sections

Topic 2—Functions » AHL 2.12—Factor and remainder theorems, sum and product of roots
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Topic 2—Functions

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