If (2, (k+1), 8,…) form an exponential sequence (GP), find the values of k.
-
A.
-3 and 5 -
B.
5 and -5 -
C.
3 and -3 -
D.
-5 and 3
Correct Answer: Option D
Explanation
Given an exponential sequence, say (a, b, c,…), as consecutive terms, then (sqrt{a times c} = b).
(therefore 2, (k+1), 8 implies sqrt{2 times 8} = k + 1)
(k + 1 = pm{4} implies k = text{-5 or 3})