Hi there everyone!(adsbygoogle = window.adsbygoogle || []).push({});

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?

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# Infinity geometric series question

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