Question

Say true or false.

If $l$ is the last term of the finite A.P., say with the $n$ terms, and the first term is $a$ then the sum of all terms of the A.P. is given by $S=\frac{n}{2}(a+l).$

• A. True
• B. False

Answer 1

The correct option is A True

General formula for sum of $n$ terms of an AP
$=\frac{n}{2}\times (2a+(n-1\left)d\right)$

$=\frac{n}{2}\times (a+a+(n-1\left)d\right)$

$=\frac{n}{2}\times (a+l)$, where $l$ is the last term.
Therefore, given statement is true.