The first three terms of a geometric series are 3(q+5), 3(q+3), (q+7) respectively.
Calulate the value of q.

Thankyou very much!

Hi,

The distinguishing feature of a geometric sequence is the common ratio, often designated r. The defining property is that if s and t are two successive terms in the sequence then

t = r s.

Thus the second term is r times the first term, and the third term is r times the second term. Hence for your sequence

3(q + 3) = r 3(q + 5)

and

(q + 7) = r 3(q + 3)

From the first equation

r = ^{(q + 3)}/_{(q + 5)}

and from the second equation

r = ^{(q + 7)}/_{3(q + 3)}

Thus

 ^{(q + 3)}/_{(q + 5)} =  ^{(q + 7)}/_{3(q + 3)}

Solve for q.

Penny

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