The sum of the first $n$ terms of the arithmetic series $1 + 2 + 3 + 4 + \ldots$ is —

Question

Accepted Answer

$\dfrac{n(n+1)}{2}$

Answer

$\dfrac{n(n-1)}{2}$

Answer

$n^2$

Answer

$\dfrac{n^2 + 1}{2}$

The sum of the first nnn terms of the arithmetic series 1+2+3+4+…1 + 2 + 3 + 4 + \ldots1+2+3+4+… is —