Question

Find Sn for the given arithmetic series.
01 = -40, d = -7, n = 22

Answer 1

`\large \boxed{-187}`

Explanation:

The formula for the sum of n terms of an arithmetic sequence is

aₙ = a₁ + (n-1)d

If a₁ = -40, d = -7, and n = 22

`\begin{array}{rcl}S_(22) & = & -40 + (22 - 1)(-7)\\& = &-40 + 21(-7)\\& = & -40 - 147\\& = & \mathbf{-187}\\\end{array}\\ \text{The sum of the first 22 terms is $\large \boxed{\mathbf{-187}}$}`