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Date May Example question Marks available 1 Reference code EXM.1.AHL.TZ0.16
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Write down Question number 16 Adapted from N/A

Question

Find a relationship between a and b if the matrices M=(1a23) and N=(1b23) commute under matrix multiplication.

[4]
a.

Find the value of a if the determinant of matrix M is −1.

 

[2]
b.i.

Write down M1 for this value of a.

[1]
b.ii.

Markscheme

(1a23)(1b23)=(1+2ab+3a82b+9)

(1b23)(1a23)=(1+2ba+3b82a+9)        M1A1

So require a=b        M1A1

[4 marks]

a.

|1a23|=32a=1a=2       M1A1

[2 marks]

b.i.

(1223)1=(3221)       A1

[1 mark]

b.ii.

Examiners report

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

Syllabus sections

Topic 1—Number and algebra » AHL 1.14—Introduction to matrices
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Topic 1—Number and algebra

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