Thread: Another Arithmetic series question.....

If the limiting sum of the series a +ar + ar^2 +......... is x, then show S_n = [x^n - (x-a)^n]/ x^(n-1)

Thanks for any help......

Originally Posted by anonymous_maths

If the limiting sum of the series a +ar + ar^2 +......... is x, then show S_n = [x^n - (x-a)^n]/ x^(n-1)

Thanks for any help......

. Re-arrange to make the subject.

Substitute this expression for into the usual formula for and simplify.