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Slove 8 and 9 Please!

 Apr 14, 2019
 #1
avatar+102948 
+3

8)   Let the first term  =  a

Then we know that the second term = ar = 42     where r is the common difference

And the sixth term  = 6302.625  = ar^5

 

So.....we have the following equations

ar  =  42

ar^5 = 6302.25          divide the ssecond equation by the first and we have

 

r^4 = 6302.625 / 42  

r = ( 6302.625  / 42 )^1/4  = 3.5

 

To find the first term we can solve this

 

ar = 42

a (3.5) = 42

a = 42/3.5  = 12  = first term

 

 

cool cool cool

 Apr 14, 2019
 #2
avatar+102948 
+2

9)  Not as tough as 8

 

1st term = a  = 63      (1) 

4th term  = ar^3 = 122     (2)

 

Sub (1) into (2)

 

63r^3 = 122

r^3  = 122/63

r = (122/63)^(1/3)  ≈ 1.246 ≈  1.25

 

 

cool cool cool

 Apr 14, 2019

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