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Date November 2015 Marks available 2 Reference code 15N.1.hl.TZ0.10
Level HL only Paper 1 Time zone TZ0
Command term Find Question number 10 Adapted from N/A

Question

A given polynomial function is defined as f(x)=a0+a1x+a2x2++anxn. The roots of the polynomial equation f(x)=0 are consecutive terms of a geometric sequence with a common ratio of 12 and first term 2.

Given that an1=63 and an=16 find

the degree of the polynomial;

[4]
a.

the value of a0.

[2]
b.

Markscheme

the sum of the roots of the polynomial =6316     (A1)

2(1(12)n112)=6316     M1A1

 

Note:     The formula for the sum of a geometric sequence must be equated to a value for the M1 to be awarded.

 

1(12)n=6364(12)n=164

n=6     A1

[4 marks]

a.

a0an=2×1×12×14×18×116, (an=16)     M1

a0=16×2×1×12×14×18×116

a0=25(=132)     A1

[2 marks]

Total [6 marks]

b.

Examiners report

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

Syllabus sections

Topic 2 - Core: Functions and equations » 2.6 » Sum and product of the roots of polynomial equations.

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