Understanding Geometric Sequences with ln

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The discussion focuses on solving a problem involving geometric sequences and logarithms. The participant initially considers using the geometric series formula but is advised to simplify the sum using properties of logarithms instead. The correct answer is identified as ln(x^70/y^34), with clarification on the denominator calculation leading to y^595. The conversation highlights the importance of recognizing when to apply logarithmic identities over geometric series formulas. Overall, the thread emphasizes understanding logarithmic simplifications in the context of geometric sequences.
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Homework Statement



http://img16.imageshack.us/img16/2327/nummer1.jpg

Homework Equations


Sn=(u1(rn-1))/(r-1)

The Attempt at a Solution


I think i need to use the equation for geometric series(above). Or do i use the arithmetic furmula since ln(a/b)=ln(a)-ln(b). I think i am a bit confused...
 
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Hint: Simplify the sum using ln(a)+ln(b)=ln(a*b). You will not need the geometric series.
 
ohh, i get it. The the answer is ln(x70/y34)
Right?
Thanks for the help! you are great!:wink:
 
hostergaard said:
ohh, i get it. The the answer is ln(x70/y34)
Right?
Thanks for the help! you are great!:wink:

Well, in the denominator you should have y*(y^2)*(y^3)*...*(y^34)=y^595. Here I am using the formula 1+2+3+...+n=n(n+1)/2.
Glad I could help. :smile:
 

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