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Maximum Value (Posted on 2002-06-19) Difficulty: 3 of 5
We have :
      x^2+xy+y^2=3 and
      y^2+yz+z^2=16
      A=xy+yz+zx
Find the maximum value of A. Find x, y and z when A=max value.

(Remember the category)

  Submitted by vohonam    
Rating: 3.2857 (7 votes)
Solution: (Hide)
The maximum value is 8.

There are two sets of values that yield this value:

(x, y, z) = (7/√31, 4/√31, 20/√31)
and 
(x, y, z) = (-7/√31, -4/√31, -20/√31)
Brian Smith offers a three-part solution here, here, and here.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Puzzle AnswerK Sengupta2022-04-12 01:56:47
SolutionSolution: Part 3Brian Smith2003-09-04 12:01:53
SolutionSolution: Part 2Brian Smith2003-09-04 11:46:19
SolutionSolution: Part 1Brian Smith2003-09-04 11:15:27
Some Thoughtsre: Most of a solution - Solution confimed.Brian Smith2003-04-28 04:13:15
re(2): Most of a solutionBrian Smith2003-04-09 05:29:11
re: Most of a solutionCory Taylor2003-04-09 04:21:56
Some ThoughtsMost of a solutionBrian Smith2003-04-08 09:59:54
re: Who can do this ?Cory Taylor2002-11-15 03:56:38
Some ThoughtsNo Subjectlucky2002-06-23 07:48:58
QuestionWho can do this ?vohonam2002-06-20 18:22:23
Hints/Tipsre: Methods to solve thisvohonam2002-06-19 17:28:58
Hints/TipsMethods to solve thisvohonam2002-06-19 17:27:00
re(3): Oooo... Getting schmancy, are we?friedlinguini2002-06-19 08:12:06
Questionre(2): Oooo... Getting schmancy, are we?levik2002-06-19 07:48:07
re: Oooo... Getting schmancy, are we?friedlinguini2002-06-19 06:59:47
re(2): Oooo... Getting schmancy, are we?friedlinguini2002-06-19 05:00:25
re: Oooo... Getting schmancy, are we?levik2002-06-19 04:36:53
Some ThoughtsOooo... Getting schmancy, are we?friedlinguini2002-06-19 04:18:57
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