Question
Find n for the arithmetic series with Sn = 360, a1=42 and an= -26
Answers
Steve
S<sub>n</sub> = n/2 (a<sub>1</sub> + a<sub>n</sub>)
360 = n/2(42 - 26)
360 = 8n
n = 45
360 = n/2(42 - 26)
360 = 8n
n = 45
Anonymous
May I ask how did you get that 8n...I'm having trouble working it out on paper for another problem