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Date May Example question Marks available 6 Reference code EXM.1.AHL.TZ0.34
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Show that Question number 34 Adapted from N/A

Question

The square matrix X is such that X3 = 0. Show that the inverse of the matrix (I X) is I + X + X2.

Markscheme

For multiplying (I X)(I + X + X2)       M1

= I2 + IX + IX2  XIX2  X3 = I + X + X2 – XX2 – X3         (A1)(A1)

= I X3         A1

= I        A1

AB = I ⇒ A–1 = B        (R1)

(I X) (I + X + X2) = I ⇒ (I X)–1 = I + X + X2          AG   N0

[5 marks]

Examiners report

[N/A]

Syllabus sections

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