ECZ 2016 · O-Level Paper 2 · Question 1 — Matrices

Matrix Q = 3-2x4.

(a(i)) Given that matrix Q = 3-2x4, find the value of x, given that the determinant of Q is 2.[2]

Verified working — step 1

det Q = (3)(4) - (-2)(x) = 12 + 2x

(a(ii)) Find the inverse of Q.[2]

Verified working — step 1

With x = -5, Q = 3-2-54 and det Q = …

(b) Solve the equation x2 + 2x = 7, giving your answers correct to 2 decimal places.[5]

Verified working — step 1

x2 + 2x - 7 = 0, so a = 1, b = 2, c = -7.

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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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