Find the sum `Sigma_(j=1)^(n) Sigma_(i=1)^(n) I xx 3^j`

sum_(j=1)^(n)sum_(i=1)^(n)i=

Find the sum sum_(0<=i

If b_i=1-a_i na = Sigma_(i=1)^(n) a_i, nb = Sigma_(i=1)^(n) b_i " then " Sigma_(i=1)^(n) a_b_i+Sigma_(i=1)^(n)(a_i-a)^2=

Find the sum sum_(0<=i

Find the sum Sigma_(n=1)^(oo)(3n^2+1)/((n^2-1)^3)

Find the sum Sigma_(r=1)^(oo)(3n^2+1)/((n^2-1)^3)

Find the sum Sigma_(r=1)^(oo)(3n^2+1)/((n^2-1)^3)

Find the sum sum_(0<=i

Find the sum sum sum_(0<=i