ECZ 2019 · GCE Paper 1 — Matrices
Given that R = [2 −1; 1 3] and S = [1 0 −4; −2 1 1] (rows separated by semicolons), find RS.
- A. [2 0 4; −2 3 3]
- B. [4 1 −9; −5 3 −1]
- C. [0 −1 −9; 7 3 −1]
- D. [4 −1 −9; −5 3 −1]
Verified working — step 1
Each row of R multiplies each column of S. Row 1: (2)(1)+(−1)(−2) = 4; (2)(0)+(−1)(1) = −1; (2)(−4)+(−1)(1) = −9. Row 2: (1)(1)+(3)(−2) = −5; (1)(0)+(3)(1) = 3; (1)(−4)+(3)(1) = −1. So RS = …The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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