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Date November 2018 Marks available 3 Reference code 18N.2.AHL.TZ0.H_6
Level Additional Higher Level Paper Paper 2 Time zone Time zone 0
Command term Find Question number H_6 Adapted from N/A

Question

Let P(x)=2x415x3+ax2+bx+c, where abcR

Given that (x5) is a factor of P(x), find a relationship between a, b and c.

[2]
a.

Given that (x5)2 is a factor of P(x), write down the value of P(5).

[1]
b.

Given that (x5)2 is a factor of P(x), and that a=2, find the values of b and c.

[3]
c.

Markscheme

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

attempt to substitute x=5 and set equal to zero, or use of long / synthetic division      (M1)

2×5415×53+a×52+5b+c=0      A1

(25a+5b+c=625)

 

[2 marks]

a.

0     A1

 

[1 mark]

b.

EITHER

attempt to solve P(5)=0     (M1)

8×5345×52+4×5+b=0

 

OR

(x210x+25)(2x2+αx+β)=2x415x3+2x2+bx+c      (M1)

comparing coefficients gives α = 5, β = 2

 

THEN

b = 105      A1

c=62525×2525

c = 50      A1

 

[3 marks]

c.

Examiners report

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

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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