Question

Find the sum of series 7² + 9² + 11²..... n term

Answer 1

Sum of odd square Numbers= (Sum of Squares of all 2n numbers) - (Sum of squares of first n even numbers)
        = 2n*(2n+1)*(2*2n + 1)/6 - 2n(n+1)(2n+1)/3
        = 2n(2n+1)/6 [4n+1 - 2(n+1)]
        = n(2n+1)/3 * (2n-1)
        = n(2n+1)(2n-1)/3