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: Option B
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)