Question

what is the sum of the infinite arithmetic series?
(-5)+0+5+10+...+65
a.900
b.455
c.450
d.445

Answer 1

This is not an infinite series...

Answer 2

yes it is

Answer 3

No, it's not. It's finite. If \(a_n\) gives the \(n\)th term in the series, then
\[a_1=-5\\
a_2=-5+5=0\\
a_3=-5+5(2)=5\\
\quad~~\vdots\\
a_n=-5+5(n-1)\]
From the last equation, you can determine how many terms are in the series.
\[65=-5+5(n-1)\]
Clearly \(n\) is a finite number.