SOLUTION: Find 2 geometric means between 9 and -1944

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Question 956094: Find 2 geometric means between 9 and -1944
Answer by Edwin McCravy(20056) About Me  (Show Source):
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9 and -1944

The sequence is

a1, a2, a3, a4

where the two middle terms are the two geometric means.

Using the formula for the nth term

a1, a1r, a1r², a1r³

a1 = 9, 

So the sequence is

9, 9r, 9r², 9r³

a4 = 9r³ = -1944
      r³ = -216
       r = -6

The two means are 9r and 9r², which are

           9(-6) = -54 and 9(-6)² = 9(36) = 324 

Edwin