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by nafiul9090 » Sat Apr 16, 2011 10:17 am
What is the difference between the sixth and the fi fth
terms of the sequence 2, 4, 7, ... whose nth term is
n + 2^n - 1 ?
(A) 2
(B) 3
(C) 6
(D) 16
(E) 17

here 1st term = 2
2nd= 4
3rd=7
4th=11
5th= 16
6th= 22


in that case the difference between 5th and 6th terms is 22-16=6

wht am i missing???
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by vineeshp » Sat Apr 16, 2011 10:34 am
Check the math again. I am assuming that the -1 is in the power.

If -1 is in the power.
2nd term is 2 + 2^2-1 = 2 + 2^1 = 4.
4th term is 4 + 2^3 = 12.

If -1 is in the expression
2nd term is 2 + 2^2-1 = 2 + 4 - 1 = 5. I dont think it is in the expression. So I think ur calculation for 4th term is wrong.
Vineesh,
Just telling you what I know and think. I am not the expert. :)
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by arunpanda22 » Sat Apr 16, 2011 7:29 pm
why work soo much
formula given is n+2^n-1
fifth term= 5+2^4
sixth term= 6+2^5
difference=6+32-5-16=1+16=17
so ans is e
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