Question about max of functions

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SUMMARY

The discussion centers on finding the maximum of functions defined over specific intervals in real numbers. The user seeks to derive a formula for the maximum of multiple variables, specifically max{x,y,z} and extends this to n variables. The well-known formula for two variables, max(x,y) = (x+y+|x-y|)/2, is referenced as a starting point. The conclusion drawn is that the maximum of n variables can be expressed as max{x_1, x_2, ..., x_n} = (Σx_i + |x_i - x_j| for all i,j) / 2, though the exact formulation requires further clarification.

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alomari2010
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Let a,b,c,d in R. For a=< x =< b and c=< y =< d, find

maxx{maxy{(x-a)(y-c), (x-a)(d-y), (b-x)(y-c), (b-x)(d-y)}}??

it is well known that

max(x,y) = [tex]\frac{x+y+|x-y|}{2}[/tex]
 
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alomari2010 said:
Let a,b,c,d in R. For a=< x =< b and c=< y =< d, find

maxx{maxy{(x-a)(y-c), (x-a)(d-y), (b-x)(y-c), (b-x)(d-y)}}??

it is well known that

max(x,y) = [tex]\frac{x+y+|x-y|}{2}[/tex]

With x fixed the functions you have are just straight lines... very easy to find max and min!

maxx{maxy{(x-a)(y-c), (x-a)(d-y), (b-x)(y-c), (b-x)(d-y)}}=
maxx{(x-a)(d-c), (x-a)(d-c), (b-x)(d-c), (b-x)(d-c)}=
max{(b-a)(d-c), (b-a)(d-c), (b-a)(d-c), (b-a)(d-c)}=:biggrin:=(b-a)(d-c)
 
Thanks!

but i think you didn't got what i want!

i will try to repost my Q?

As above we have a formula for max{x,y}. So what is the formula for max{x,y,z}?
where x,y,z in R. In general, for x_i in R, i=1,2,..,n
what is the formula for max{x_1, x_2,..., x_n}?

hope anyone can got the answer!
 

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