January 2nd, 2017, 01:05 PM  #1 
Member Joined: May 2016 From: Ireland Posts: 96 Thanks: 1  maximum
of all numbers whose sum is 80 find the two that have the maximum product that is; maximise p=xy where x+y=80 I know the answer is 40 by just looking at it but is there a algebraically way to di it 
January 2nd, 2017, 01:19 PM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 2,701 Thanks: 1359 
$x+y = 80 \implies y = 80x$ $xy = p = x(80x) = 80xx^2$ the graph of $p$ is an inverted parabola with a maximum value at its vertex ... how do you find the vertex and determine the maximum for $p$ ? 

Tags 
maximum 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Maximum value  Ionika  Trigonometry  1  February 25th, 2015 11:52 AM 
Maximum value  panky  Calculus  1  October 22nd, 2014 09:36 PM 
Difference Between Maximum/Minimum Value and Maximum/Minimum Turning Point  Monox D. IFly  PreCalculus  4  October 13th, 2014 06:58 AM 
Maximum value  panky  Trigonometry  5  August 4th, 2014 05:51 PM 
Maximum  Denis  Algebra  1  November 26th, 2011 03:42 AM 