User interface language: English | Español

Date May Example question Marks available 4 Reference code EXM.1.AHL.TZ0.16
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number 16 Adapted from N/A

Question

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

[4]
a.

Find the value of aa if the determinant of matrix MM is −1.

 

[2]
b.i.

Write down M1M1 for this value of aa.

[1]
b.ii.

Markscheme

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

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

So require a=ba=b        M1A1

[4 marks]

a.

|1a23|=32a=1a=21a23=32a=1a=2       M1A1

[2 marks]

b.i.

(1223)1=(3221)(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
Show 139 related questions
Topic 1—Number and algebra

View options