ECZ 2018 · GCE Paper 2 · Question 1 — Matrices

Matrix A = 2x23x.

(a(i)) Find the positive value of x for which the determinant of A is 12.[2]

Verified working — step 1

det(A) = (2x)(x) - (2)(3) = 2x2 - 6

(a(ii)) Hence or otherwise, write A-1.[2]

Verified working — step 1

With x = 3, A = 6233, det(A) = 12

(b) Solve the equation x2 - 4x - 2 = 0, giving your answers correct to 2 decimal places.[5]

Verified working — step 1

x2 - 4x - 2 = 0

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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