Question

Find the sum of the arithmetic series in which a1 = –68, d = –3, and n = 20.

Answer 1

-1930

Explanation:

Answer 2

Sum = -1930

Explanation:

Sum of an arithmetic series;

;Sum = n/2[ 2a1 + ( n - 1 )d]

Then substitute into the equation above

; Sum = 20/2 [ 2(-68) + (19)-3 ]

; Sum = 10 [ -136 - 57 ]

Therefore the sum of the arithmetic series

is....; -1930