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Date May Example question Marks available 2 Reference code EXM.1.AHL.TZ0.43
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number 43 Adapted from N/A

Question

Find the values of a and b given that the matrix A=(a46857534) is the inverse of the matrix B=(1223b1113).

[2]
a.

For the values of a and b found in part (a), solve the system of linear equations

x+2y2z=53x+by+z=0x+y3z=a1.

[2]
b.

Markscheme

AB = I

(AB)11 = 1 ⇒ a – 12 + 6 = 1,    giving a = 7          (A1) (C1)

(AB)22 = 1 ⇒ –16 + 5b + 7 = 1,    giving b = 2          (A1) (C1)

[2 marks]

a.

the system is BX=(506) where X=(xyz).

Then, X=A(506)=(746857534)(506).          (M1)

Thus x=1y=2z=1          (A1) (C2)

[2 marks]

b.

Examiners report

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

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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