Math CentralQuandaries & Queries


Question from Abeth, a teacher:

find the value of x so that 2(x-1), x+3, x will be a geometric progression.


In each geometric progression there is a common ratio r that is used to proceed from any term to the next. If some term is p then the next term is p × r.

In your geometric progression the firs term is 2(x - 1) and the second term is x + 3. If the common ratio is r then what is the second term in terms of the first term? What is the third term in terms of the second term?

This gives you two equations in the variables x and r. Solve for x.


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