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Please Solve

 

Thank you

 Sep 17, 2017
 #1
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+1

 

Let b1  = a

 

So....b3  =   ar*2   and b5  = ar*4

 

So

 

ar^2 -   a  =   16  →    a [r^2 - 1] = 16   →    a  = 16 / [ r^2 - 1 ]   (1)

 

ar^4 - ar^2  =  144→  a [ r^4 - r^2]  =  144 → a = 144 / [ r^4 - r^2]     (2)

 

Equating (1)  and (2)  we have that

 

16 / [ r^2 - 1 ]   =  144 / [ r^4 - r^2]    cross-multiply

 

16  [ r^4 - r^2]  =  144 [ r^2 - 1 ]    simplify

 

16r*2 [ r^2 - 1] = 144 [r^2- 1]       divide through  by  16

 

r^2 [ r^2 - 1]  = 9 [r^2 - 1]       divide through by [ r^2 - 1]

 

r^2  =  9   →   r  =  3  or  -3

 

If r  = ±3,  then b1 =  a =  16 / [ 3^2 - 1]  =  16 / 8  =  2 

 

 

 

cool cool cool

 Sep 17, 2017

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