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Mathematical Analysis Problem: Proving Stuff

KingAgamemnonKingAgamemnon Registered User regular
edited February 2008 in Help / Advice Forum
So, I need to understand how to prove an inequality. Here it is:

Prove that for REALS: a,b,c,d

a/b<(a+b)/(c+d)<c/d with b,d>0

I thought I would first prove it from right to left then left to right, but I spent like an hour algebraically manipulating the left side without getting anywhere that I could see. I don't need the whole proof, just a strong hint on how to prove something is less than something else. Or the whole proof if you really like.

In conclusion: I no good at proof. Help.

KingAgamemnon on


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    musanmanmusanman Registered User regular
    edited February 2008
    I started with a/b < c/d and
    by adding c/b to both sides

    could work back to (a+c)/(b+d) < c/d

    I suppose you could do the same thing with the other side of the equation, since this is basically two proofs (you essentially have an and statement).

    musanman on
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