Answer:
40 terms
Step-by-step explanation:
the sum to n terms of an arithmetic sequence is
[tex]S_{n}[/tex] = [tex]\frac{n}{2}[/tex] (a₁ + [tex]a_{n}[/tex] )
then
[tex]\frac{n}{2}[/tex] (- 4 - 82) = - 1720 ( multiply both sides by 2 to clear the fraction )
- 86n = - 3440 ( divide both sides by - 86 )
n = 40
the series has 40 terms
