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Levans writes a positive fraction in which the numerator and denominator are integers, and the numerator is 2 greater than the denominator.  He then writes several more fractions.  To make each new fraction, he increases both the numerator and the denominator of the previous fraction by 1  He then multiplies all his fractions together.  He has 3 fractions, and their product equals 4. What is the value of the first fraction he wrote?

 
 Dec 27, 2024
 #1
avatar+129933 
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(n+ 2)/(n ) * (n + 3) / (n + 1) * (n + 4) / ( n + 2)  = 4          simplify as

 

 (n + 3) *(n + 4)  =  4 (n)(n + 1)

 

n^2 +7n +12  =  4n^2 + 4n

 

3n^2 - 3n - 12 = 0

 

n^2 - n - 4  = 0

 

n^2 - n +1/4  =   4

 

(n - 1/2)^2  =  +/- 17/4

 

n =  [1 + sqrt (17)] /2                     or     n = [ 1 -sqrt (17) ] /2

 

No integer values for numerator/denominator  are possible

 

cool cool cool

 Dec 28, 2024

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