The first term of a linear sequence is 9 and the common difference is 7.
FURTHER MATHEMATICS
WAEC 2014
The first term of a linear sequence is 9 and the common difference is 7. If the nth term is 380, find the value of n.
- A. 45
- B. 54
- C. 56
- D. 65
Correct Answer: B. 54
Explanation
\(T_{n} = a + (n - 1)d\)
\(380 = 9 + (n - 1)7\)
\(380 = 9 + 7n - 7 \implies 380 = 2 + 7n\)
\(7n = 380 - 2 = 378 \therefore n = \frac{378}{7} = 54\)
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