If f(n)=f(n−1)+2n−1f(n) = f(n-1) + 2n - 1f(n)=f(n−1)+2n−1 and f(0)=0f(0) = 0f(0)=0, what is the closed form?
2n2n2n
n2−1n^2 - 1n2−1
n2n^2n2
n2+1n^2 + 1n2+1