The sum, \(S_{n}\), of a sequence is given by \(S_{n} = 2n^{2} - 5\). Find...
FURTHER MATHEMATICS
WAEC 2015
The sum, \(S_{n}\), of a sequence is given by \(S_{n} = 2n^{2} - 5\). Find the 6th term.
- A. 112
- B. 67
- C. 45
- D. 22
Correct Answer: D. 22
Explanation
\(S_{n} = 2n^{2} - 5\)
\(T_{n} = S_{n} - S_{n - 1}\)
\(T_{6} = S_{6} - S_{5}\)
= \((2(6^{2} - 5) - (2(5^{2} - 5) = 62 - 40 = 22\)
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