Question
Find sum of series..1*(n)2 + 2*(n-1)2 +3*(n-2)2 +...+n .
Joshi sir comment
general term of the series = r(n+1-r)2 = r(n+1)2 + r3 - 2(n+1)r2
now put sigma then solve
Find sum of series..1*(n)2 + 2*(n-1)2 +3*(n-2)2 +...+n .
general term of the series = r(n+1-r)2 = r(n+1)2 + r3 - 2(n+1)r2
now put sigma then solve