extra info in a question.

This topic has expert replies
Legendary Member
Posts: 876
Joined: Thu Apr 10, 2008 8:14 am
Thanked: 13 times

extra info in a question.

by ketkoag » Wed Mar 25, 2009 2:25 am
A certain computer program generates a sequence of numbers a1, a2, … , an such that a1 = a2 = 1
and ak = ak-1 + 2ak-2 for all integers k such that 3< &#155; &#155;&#155;&#155;&#155;&#155; k &#155;< n. If n <6, then a7 = ?
A. 32
B. 43
C. 64
D. 100
E. 128

I got the right answer that is b by simply calculating the value for a7, but please explain me why the information n < 6 is given in the question as it is not been used.
Please explain the solution if this info is necessary.....
Source: — Problem Solving |