Determine the first term of this infinite geometric series if 𝑆2=72 and 𝑟=−35 . To what value does the series converge?

Answer 1

a1 +a2 = 72 r=-35

a1 + a1(-35) = 72

-34a1 = 72

a1 = 72/-34 = -36/17

a2 = -35(-36)/17 = 1332/17

an = (-36/17)(-35)^(n-1)

the series diverges, never converges

terms change sign, with absolute values approaching infinity