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Date May 2013 Marks available 3 Reference code 13M.1.sl.TZ2.3
Level SL only Paper 1 Time zone TZ2
Command term Find Question number 3 Adapted from N/A

Question

Let log3p=6 and log3q=7 .

Find log3p2 .

[2]
a.

Find log3(pq) .

[2]
b.

Find log3(9p) .

[3]
c.

Markscheme

METHOD 1

evidence of correct formula     (M1)

eg   logun=nlogu , 2log3p

log3(p2)=12     A1     N2

METHOD 2

valid method using p=36     (M1)

eg log3(36)2 , log312 , 12log33

log3(p2)=12     A1     N2

[2 marks]

 

a.

METHOD 1

evidence of correct formula     (M1)

eg   log(pq)=logplogq , 67

log3(pq)=1     A1     N2

METHOD 2

valid method using p=36 and q=37     (M1)

eg   log3(3637) , log31 , log33

log3(pq)=1     A1     N2

[2 marks]

 

b.

METHOD 1

evidence of correct formula     (M1)

eg   log3uv=log3u+log3v , log9+logp

log39=2 (may be seen in expression)     A1

eg   2+logp

log3(9p)=8     A1     N2

METHOD 2

valid method using p=36     (M1)

eg   log3(9×36) , log3(32×36)

correct working     A1

eg   log39+log336 , log338

log3(9p)=8     A1     N2

[3 marks]

Total [7 marks]

c.

Examiners report

This question proved to be surprisingly challenging for many candidates. A common misunderstanding was to set p equal to 6 and q equal to 7. A large number of candidates had trouble applying the rules of logarithms, and made multiple errors in each part of the question.  Common types of errors included incorrect working such as log3p2=36 in part (a), log3(pq)=log36log37 or log3(pq)=log36log37 in part (b), and log3(9p)=54 in part (c).
a.
This question proved to be surprisingly challenging for many candidates. A common misunderstanding was to set p equal to 6 and q equal to 7. A large number of candidates had trouble applying the rules of logarithms, and made multiple errors in each part of the question.  Common types of errors included incorrect working such as log3p2=36 in part (a), log3(pq)=log36log37 or log3(pq)=log36log37 in part (b), and log3(9p)=54 in part (c).
b.
This question proved to be surprisingly challenging for many candidates. A common misunderstanding was to set p equal to 6 and q equal to 7. A large number of candidates had trouble applying the rules of logarithms, and made multiple errors in each part of the question.  Common types of errors included incorrect working such as log3p2=36 in part (a), log3(pq)=log36log37 or log3(pq)=log36log37 in part (b), and log3(9p)=54 in part (c).
c.

Syllabus sections

Topic 1 - Algebra » 1.2 » Laws of exponents; laws of logarithms.
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