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The sequence 6,-9,x,y is such that the first three terms form an arithmetic sequence and the last three terms form a geometric sequence. Find x and y.

Express your answer as x,y

 Feb 23, 2019
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The common difference is second term - first term =   - 9 - 6 =   - 15

 

So the third term is  -9 - 15  = -24

 

And the common ratio   is  third term / second term =   -24 /-9 =  8/3

 

So....the fourth term is   -24 (8/3) =  -64

 

So   x , y   =      -24, -64  

 

 

cool cool cool

 Feb 23, 2019

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