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If 2,(k+1),8,... form an exponential sequence (GP), fi...

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 is D

Given an exponential sequence, say a,b,c,..., as consecutive terms, then a×c=b.

k + 1 = \pm{4} \implies k = \text{-5 or 3}