let S be the sum of N terms of the following series s(n)=2^66-2^65-2^64.what is the sum of s(20)
a- 2^47
b- 2^12
c- 2^19
d none of these set

X is having 2000 elements in AP with the first term =1. what is the max number of elements set Y can have such that sun of no twi elements of Y is equal to 9 or a multiple of 9
a 890
b 891
.c 892
d none of these

in a sequence of terms a1,a2,a3,a4...the nth term ,a(n) for n >1,is given by a(n)=a(n-1)+a(n+1).if a7=6 and a14 =7find s26/s13 where si is the sum of all the terms from a1 to ai
a1/6
b -1/6
c 13/6
d cannot b determined