`a_k=1/(k(k+1))` for `k=1,2,3,4,...n` then `(sum_(k=1)^n a_k)^2=`

sum_(k=1)^n k^3=

For any integer n>=1, then sum_(k=1)^(n)k(k+2)=

Evaluate : sum_(k=1)^n (2^k+3^(k-1))

Let a_(k)=.^(n)C_(k) for 0<=k<=n and A_(k)=[[a_(k-1),00,a_(k)]] for 1<=k<=n and B=sum_(k=1)^(n-1)A_(k)*A_(k+1)=[[a,00,b]]

If sum_(k=1)^(n)k=210, find the value of sum_(k=1)^(n)k^(2).

sum_(k=1)^(2n+1)(-1)^(k-1)k^(2)=

If Delta_(k) = |(k,1,5),(k^(2),2n +1,2n +1),(k^(3),3n^(2),3n +1)|, " then " sum_(k=1)^(n) Delta_(k) is equal to

If sum_(k=1)^(n)k=45, find the value of sum_(k=1)^(n)k^(3).