For an AP, the sum of n terms can also be written as S_n = n/2(a + l), where l is the:

last term. When the last term l is known, S_n = n/2(a + l), where l is the last (nth) term.

For an AP, the sum of $n$ terms can also be written as $S_{n} = \frac{n}{2}$ $(a + l)$ , where $l$ is the:

Class 10Sum of n Terms of an APAlgebra — Sequences

When the last term

l

is known,

S_{n} = \frac{n}{2}

(a + l)

, where

l

is the last (nth) term.

Answer: A) last term

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