How to "show" something in math

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Belegost

Golden Member
Feb 20, 2001
1,807
19
81
The problem states that the variables are nonnegative numbers, which means they are equal to or greater then zero. However, in my proof I can see no reason the numbers cannot equal zero.
 

thEnEuRoMancER

Golden Member
Oct 30, 2000
1,415
0
71
a <= (b+c)

a/(1+a) <= ((b/(1+b)) + (c/(1+c)))

transform this to:

1/(1+1/a) <= (1/(1+1/b) + 1/(1+1/c))

multiply both sides with (1+1/a)*(1+1/b)*(1+1/c) to get

(1+1/b)*(1+1/c) <= (1+1/a)*(1+1/c) + (1+1/a)*(1+1/b)

1 + 1/b + 1/c + 1/(bc) <= 1 + 1/a + 1/c + 1/(ac) + 1 + 1/a + 1/b + 1/(ab)

1/(bc) <= 1 + 2/a + 1/(ac) + 1/(ab)

multiply both sides with abc to get

a <= abc + 2bc + b + c

now a <= b+c , so if we add abc + 2bc to the right side of inequality it will still hold
 

aolj

Golden Member
Feb 20, 2000
1,383
0
76
If I'm not wrong, you could show the solution by induction method.
Thing is it's raining here and I've got to go. Hopefully, I can show it soon.

later.
 

serialb

Diamond Member
Mar 20, 2000
3,107
7
81
Just wonder what class is GoldenBear in? Assuming you are a computer science junior, you should have taken discrete math. As aolj stated, mathematical induction will solve the problem in a simple and logical way. Go do a little search in google and I bet you will find some information on MI.