`1-sum_(k=1)^9 cos\ (2pik)/10` equals to…..

In Q. No. 121, 1-sum_(k=1)^(9)cos(2kpi)/10 equals

The value of \lim_{n \to \infty } sum_(k=1)^n (n-k)/(n^2) cos((4k)/n) equals to

("lim")_(x->oo)sum_(x=1)^(20)cos^(2n)(x-10) is equal to (a) 0 (b) 1 (c) 19 (d) 20

If S_n=sum_(k=1)^n a_k and lim_(n->oo)a_n=a , then lim_(n->oo)(S_(n+1)-S_n)/sqrt(sum_(k=1)^n k) is equal to

sum_(k=0)^(5)(-1)^(k)2k

The sum sum_(k=1)^oocot^(-1)(2k^2) equals

sum_(i=1)^(oo)sum_(j=1)^(oo)sum_(k=1)^(oo)(1)/(a^(i+j+k)) is equal to (where |a| gt 1 )

If sum_(r=1)^(oo)(1)/((2r-1)^(2))=(pi^(2))/(8) , then sum_(r=1)^(oo) (1)/(r^(2)) is equal to

The value of sum_(k=1)^(3) cos^(2)(2k-1)(pi)/(12), is

sum_(r=1)^(n) r^(2)-sum_(r=1)^(n) sum_(r=1)^(n) is equal to