[" If "S_(n)=sum_(r=1)^(n)(2r-1)/(r^(4)+2r^(3)+r^(2))" then "S_(20)" is equal "],[" to- "]

If S_(n)=sum_(r=1)^(n)(2r+1)/(r^(4)+2r^(3)+r^(2)), then S_(10) is equal to

If S_(n)=sum_(r=1)^(n)(1+2+2^(2)+2^(3)+.... rterms )/(2^(r)) then S_(-)n is equal to

if S_(n)=sum_(r=1)^(n)(1+2+2^(2)......... rterms )/(2^(r)) then S_(n) is equal to

If S_(n) = sum_(r=1)^(n) (r )/(1.3.5.7"……"(2r+1)) , then

If sum_(r=1)^(r=n)(r^(4)+r^(2)+1)/(r^(4)+r)=(675)/(26), then n is equal to

If S_(n)=sum_(r=1)^(n)(1+2+2^(2)+......+2^(r))/(2^(r)), then S_(n) is equal to (a)2^(n)n-1( b) 1-(1)/(2^(n))(c)2n-1+(1)/(2^(n))(d)2^(n)-1

S_(n)=sum_(r=1)^(n)(r)/(1.3.5.7......(2r+1)) then

If sum_(s=1)^(n){sum_(r=1)^(s)r}=an^(3)+bn^(2)+Cn then