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ratio of 5 to 4 with product of 81

 Jan 5, 2017
 #1
avatar+129656 
0

This  ???

 

(5/4) * 81  =

 

405 / 4  =

 

101 + 1/4

 

 

 

cool cool cool

 Jan 5, 2017
 #2
avatar+118629 
0

I do not ever remember seeing a question like this before :)

 

ratio of 5 to 4 with product of 81

Let the numbers be   (5x/9) and  (4x/9)

This has nothing to do with the 81.  The nine comes from   4+5=9

 

\(\frac{5x}{9}\times \frac{4x}{9}=81\\ \frac{20x^2}{81}=81\\ 20x^2=81^2\\ 20x^2=6561\\ x^2=328.05\\ x=\sqrt{32805}\div10\)

 

factor(32805) = 3^8*5

 

\(x=\frac{\sqrt{81*81*5}}{10}\\ x=\frac{81\sqrt{5}}{10}\\\)

 

so the numbers are 

\(\frac{5}{9}\;of\; 8.1\sqrt5 \quad and \qquad \frac{4}{9}\;of\; 8.1\sqrt5\\ \quad4.5\sqrt5 \qquad and \qquad 3.6\sqrt5\\\)

 

check

4.5*sqrt(5)*3.6*sqrt(5) = 81

and

4.5*sqrt(5)/(3.6*sqrt(5)) = 1.25 = 5/4

 

*

 Jan 6, 2017

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