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The numbers a, b, c and d form a geometric sequence, in that order. If b is 3 more than a, and c is 9 more than b, what is the value of d? Express your answer as a mixed number.

 
 Jul 21, 2021
 #1
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0

As a mixed number, d = 22 1/2.

 
 Jul 21, 2021
 #2
avatar+33360 
+2

a * r  = a +3  

a * r * r = a+3 + 9     

(a+3) * r = a + 12

r = (a+12)/(a+3)

 

 

a ( a+12)/(a+3) = a + 3

a^2 + 12a = a^2 +6a + 9

          6a = 9

             a = 3/2         

 

    3/2  * r = 3/2 + 3

            r = 9/2 * 2/3 = 3

 

                                     a        b         c            d

So the sequence is     3/2     9/2     27/2      81/2              d = 40 1/2

 
 Jul 21, 2021
 #3
avatar+25 
0

@ElectricPavlov Thank you for working out this question!

 
CoolBird2006  Jul 22, 2021
 #4
avatar+33360 
0

YOU are welcome !   cheeky       Thanx for the 'thanks' !

 
ElectricPavlov  Jul 22, 2021

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