Given that \(r = 2i - j\), \(s = 3i + 5j\) and \(t =
FURTHER MATHEMATICS
WAEC 2015
Given that \(r = 2i - j\), \(s = 3i + 5j\) and \(t = 6i - 2j\), find the magnitude of \(2r + s - t\).
- A. \(\sqrt{15}\)
- B. 4
- C. \(\sqrt{24}\)
- D. \(\sqrt{26}\)
Correct Answer: D. \(\sqrt{26}\)
Explanation
\(r = 2i - j , s = 3i + 5j , t = 6i - 2j\)
\(2r + s - t = 2(2i - j) + (3i + 5j) - (6i - 2j) = i + 5j\)
\(|2r + s - t| = \sqrt{1^{2} + 5^{2}} = \sqrt{26}\)
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