1.3+3.5+5.7+......to n terms.

Question

sir this question answer 1/3n(4n^2+6n-1)

Answer 1

Tn = (2n-1)(2n+1) = 4n^2-1

so

n
∑Tk = ∑4k^2-1 = 4∑k^2 - 4∑1
k=1

Now you know what ∑k^2 is and ∑1 = n