Math CentralQuandaries & Queries


Question from Camille, a student:

Find x if the sequence 5,10,x+2 is geometric.

Hi Camille,

If a sequence is geometric then there is a number $r$ so that after the first term each term is $r$ times the previous term. In your sequence the first term is 5 and the second term is 10 so what is $r?$ Now you know $r.$ The third term is $x + 2$ and the second term is 10. What is $x?$


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