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Date May 2009 Marks available 5 Reference code 09M.1.hl.TZ1.3
Level HL only Paper 1 Time zone TZ1
Command term Find Question number 3 Adapted from N/A

Question

Let \(g(x) = {\log _5}\left| {2{{\log }_3}x} \right|\) . Find the product of the zeros of g .

Markscheme

\(g(x) = 0\)

\({\log _5}\left| {2{{\log }_3}x} \right| = 0\)     (M1)

\(\left| {2{{\log }_3}x} \right| = 1\)     A1

\({\log _3}x =  \pm \frac{1}{2}\)     (A1)

\(x = {3^{ \pm \frac{1}{2}}}\)     A1

so the product of the zeros of g is \({3^{\frac{1}{2}}} \times {3^{ - \frac{1}{2}}} = 1\)     A1     N0

[5 marks]

Examiners report

There were many candidates showing difficulties in manipulating logarithms and the absolute value to solve the equation.

Syllabus sections

Topic 2 - Core: Functions and equations » 2.4 » The function \(x \mapsto {\log _a}x\) , \(x > 0\) , and its graph

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