Sunday, January 28, 2007

"GRE ALGEBRA QUESTION OF THE DAY"

The infinite sequence a1, a2,…, an,… is such that a1 = 2, a2 = -3, a3 = 5, a4 = -1, and an = an-4 for n > 4. What is the sum of the first 97 terms of the sequence?
A. 72
B. 74
C. 75
D. 78
E. 80
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2 comments:

Unknown said...

b

January 28, 2007 at 2:48 PM
Unknown said...

neha jii .....can u explane y???...ans is d
my explanation
a1+a2+a3+a4=3;a5=a1;a6=a2;a7=a3;a8=a4
a5+a6+a7+a8=3
..
..
a92+a93+a94+a95+a96=3
so a1+...a96=3*24=72
n a97=2
den ans=74

January 29, 2007 at 12:00 PM

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