Question

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

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

Answer 1

Answer: (A), (C)

The correct options are
A $\frac{n}{2}(2s+(n-1\left)d\right)$
C $\frac{n}{2}(s+t)$

The sum up to $n$ terms of an AP with first term $s$ and common difference $d$ is $\frac{n}{2}(2s+(n-1\left)d\right)$ and the sum up to $n$ terms of an AP with first term $s$ and last term $t$ is $\frac{n}{2}(s+t)$.