posted by purple1 .
find the sum of each of the following infinite series, if no sum, write no sum.
S∞ = a/(1/r) where │r│ < 1
in the first,
a = 9, r = -1/3
so sum = 9/(1 - (-1/3)) = 6.75 or 27/4
For the second one, there is no sum, since the series diverges.
notice r = 2, so it does not satisfy the condition for the formula.
I just notice a typo in my formula, should of course be
a/(1-r) where │r│ < 1
I did use it correctly in the calculations