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If x and y are positive integers such that 5x+3y=100, what is the greatest possible value of xy?

 Jan 26, 2019
 #1
avatar+4323 
+2

We have 5x+3y=100, 6x-x+3y=100, 6x+3y=100+x, 3(2x+y)=100+x, 165?

 Jan 26, 2019
 #2
avatar+103972 
+2

The greatest possible value of xy will occur when x is most nearly equal to y

 

We have that

 

x     y            xy

17   5           85

14  10        140

11   15        165

 8    20        160

 

So.....xy  is largest when x =  11 and y = 15

 

  

cool cool  cool 

 Jan 26, 2019

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