# How do I find the first term of a geometric sequence?

##### 1 Answer

Nov 15, 2015

In geometric sequences there is a case of repeated multiplication

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#### Explanation:

So the sum of the first n terms of sequence is ;

Now given you know r n and the sum you find a by re arranging

Additionally

If you re given the nth term then'

You may often has to use both these equation to get to the answer