[" 71.The sum of first n terms of the series "],[qquad [1^(2)+(1)(2)+3^(2)+(3)(4)+5^(2)+(5)(6)+7^(2)+......" when "n" is odd "]]

The sum of first backslash n' terms of the series 1^(2)+(1)(2)+3^(2)+(3)(4)+5^(2)+(5)(6)+7^(2)+ when n is odd is

The sum of n terms of the series 1^(2) - 2^(2) + 3^(2)- 4^(2) + 5^(2) -6^(2) + ….is

The sum of the first n terms of the series 1^(2)+2.2^(2)+3^(2)+2.4^(2)+5^(2)+2.6^(2)+... is

The sum of n terms of the series 1^(2)-2^(2)+3^(2)-4^(2)+5^(2)-6^(2)+... is

The sum of first n terms of the series 1^(2) + 2.2^(2) + 3^(2) + 2.4^(2) + 5^(2) + 2.6^(2) + ….is (n(n+1)^(2))/(2) when n is odd the sum is

The sum of n terms of the series (3)/(1^(2))+(5)/(1^(2)+2^(2))+ (7)/(1^(2)+2^(2)+3^(2))+.. .. .. is

The sum of first n terms of the series 1_(2) + 2.2^(2) + 3^(2) + 2.4^(2) + 5^(2) + 2.6^(2) + ...... is (n(n + 1)^(2))/4 when n is even. When n odd the sum is

The sum of first n terms of the series 1^(2) + 2.2^(2) +3^(2) + 2. 4^(2) + 5^(2) + 2. 6^(2) + "........." is ( n ( n + 1)^(2))/( 2) when n is even. When, n is odd, the sum is :