Homework Help: A proof question

1. Nov 21, 2008

transgalactic

for "a" and "b" are real numbers prove that:
http://img505.imageshack.us/img505/5329/26310844lw6.gif [Broken]

whats the meaning of MAX[a,b] and MIN[a,b]

how am i supposed to prove that

??

Last edited by a moderator: May 3, 2017
2. Nov 21, 2008

HallsofIvy

Max[a, b] is "maximum of a and b" or simply the larger of the two numbers.

You are asked to prove that max[a,b] = (1/2)(a+ b+ |a- b|)

As always with absolute value problems, break it into to cases: a> b and a< b, and show that the two sides are the same in each of those cases.

3. Nov 21, 2008

transgalactic

but there are variables
even if i presume that a>b
i cant develop into a formula
i cant put it into the given expression
??

4. Nov 21, 2008

transgalactic

the only thing i can do with the given expression
is to split |a- b| into two cases
a-b>0 ->a>b
which gives me :
(1/2)(a+ b+ a- b)=a

a-b<0 a<b:
(1/2)(a+ b-a+ b)=b

i got a similar resolt but it didnt came from
that in the i say "if a>b ..."

5. Nov 21, 2008

tiny-tim

That's a proof, isn't it?

What's wrong with that?

(and why didn't you type out the question, and make it easier for every one?)

6. Nov 21, 2008

transgalactic

in the first post i typed the question and added a link to the formula

regarding the question:
i did it correctly?