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September 14th, 2019, 12:27 PM   #1
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Proof for a challenging inequality

I have something I believe to be true, but I'm uncertain, so I'm looking for a proof.

For positive real numbers a,b,c,d
Prove that if a>=b and c<=d, then a/c <= b/d

Last edited by bluekaterpillar; September 14th, 2019 at 12:30 PM.
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September 14th, 2019, 01:12 PM   #2
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$ad\ge bc$, since $a\ge b$ and $d\ge c $. Divide both sides by $dc$ and get $\frac{a}{c} \ge \frac{b}{d}$.
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September 14th, 2019, 01:17 PM   #3
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Thanks! I can't believe I missed that.
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