Hi there everyone! Have a quick question for you. The question is: The sum to infinity of a geometric series is 9/2 The second term of the series is -2 Find the value of r, the common ratio of the series. I understand that we have to use the sum to infinity of a geometric series formula which is S(infinity) = a/1-r where a is the first term in the series and r is the common ratio. I also understand that s2 = s1*r. We're given the second term....but how do we get a? our first term? Any thoughts?