Question

The sum up to n terms of an AP with first term $a$, last term $l$ and common difference $d$ is

• A. $\frac{n}{3}(2a+(n-1\left)d\right)$
• B. $n(2a+(n-1\left)d\right)$
  
• C. $\frac{n}{2}(a+l)$
  
• D. $n(2a+(n-1\left)d\right)$

Answer 1

The correct option is C $\frac{n}{2}(a+l)$


Sum up to $n$ terms of an AP with first term $a$ and last term $l$ is,
$S_n=\frac{n}{2}(a+l)$.