Proving Inequality Challenge: $a,\,b,\,c$ | Real Numbers

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SUMMARY

The inequality challenge presented involves proving that for real numbers \(a, b, c\) where \(a \ge b \ge c > 0\), the expression $$\frac{a^2-b^2}{c}+\frac{c^2-b^2}{a}+\frac{a^2-c^2}{b}$$ is greater than or equal to \(3a - 4b + c\). This conclusion is established through algebraic manipulation and application of known inequalities. The discussion highlights the importance of understanding the relationships between the variables to effectively prove the inequality.

PREREQUISITES
  • Understanding of real number properties
  • Familiarity with algebraic manipulation techniques
  • Knowledge of inequalities, particularly the AM-GM inequality
  • Experience with mathematical proofs
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  • Study the AM-GM inequality and its applications in proving inequalities
  • Explore algebraic manipulation techniques for simplifying expressions
  • Learn about the Cauchy-Schwarz inequality and its relevance in similar problems
  • Practice proving inequalities with varying conditions on real numbers
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Mathematicians, students studying real analysis, and anyone interested in advanced algebraic inequalities will benefit from this discussion.

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Let $a,\,b,\,c$ be real numbers such that $a\ge b\ge c>0$.

Prove that $$\frac{a^2-b^2}{c}+\frac{c^2-b^2}{a}+\frac{a^2-c^2}{b}\ge 3a-4b+c$$.
 
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anemone said:
Let $a,\,b,\,c$ be real numbers such that $a\ge b\ge c>0$.

Prove that $$\frac{a^2-b^2}{c}+\frac{c^2-b^2}{a}+\frac{a^2-c^2}{b}\ge 3a-4b+c$$.
$\dfrac{a^2-b^2}{c}+\dfrac{c^2-b^2}{a}+\dfrac{a^2-c^2}{b}\geq \dfrac{a^2-b^2}{c}+\dfrac{a^2-b^2}{a}\\
=\dfrac{(a+c)(a+b)(a-b)}{ac}\geq \dfrac{(a+c)^2(a-b)}{ac}\geq \dfrac{4ac(a-b)}{ac}=4(a-b)\\
\geq 3a-4b+c$
 
Last edited:
Albert said:
$\dfrac{a^2-b^2}{c}+\dfrac{c^2-b^2}{a}+\dfrac{a^2-c^2}{b}\geq \dfrac{a^2-b^2}{c}+\dfrac{a^2-b^2}{a}\\
=\dfrac{(a+c)(a+b)(a-b)}{ac}\geq \dfrac{(a+c)^2(a-b)}{ac}\geq \dfrac{4ac(a-b)}{ac}=4(a-b)\\
\geq 3a-4b+c$

Very well done, Albert! Thanks for participating!(Cool)
 

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