Question

What is the sum of the series?
S (-5k +20)
13

Answer 1

- 10

Explanation:

Substitute k = 3, 4, 5, 6 into the expression and sum the terms, that is

(- 15 + 20) + (- 20 + 20) + (- 25 + 20) + (- 30 + 20)

= 5 + 0 - 5 - 10

= - 10