SOLUTION: What is the missing term of the geometric sequence {45,_,1620}?

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Question 1141349: What is the missing term of the geometric sequence {45,_,1620}?
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
The second term is the first term, 45, times r, the common ratio.  
So the second term must be 45r.  So the sequence is

45, 45r, 1620

The third term is the second term, 45r, times r, the common ratio.  So the third term must be 45r².  But it's also 1620.

So we have the equation:

45r%5E2=1620

Divide both sides by 45

r%5E2=36

Take square roots of both sides:

r=%22%22+%2B-+6

So the second term 45r is 45(±6) or ±270.

The sequence is either

45, 270, 1620   or 45, -270, 1620.
 
Edwin