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If x+y+z=9, where x,y,z are positive reals, maximize \({x}^{4}{y}^{3}{z}^{2}\)

Note by Archit Boobna 2 years, 1 month ago

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\(\frac{4x}{4}+\frac{3y}{3}+\frac{2z}{2}=9\)

Applying concept of weighted means

\(\huge{\frac{4\times \frac{x}{4}+3\times \frac{y}{3}+2\times \frac{z}{2}}{4+3+2}\geq [(\frac{x}{4})^{4}\times (\frac{y}{3})^{3}\times (\frac{z}{2})^{2}]^{\frac{1}{4+3+2}}}\)

\(\large{\frac{x+y+z}{9} \geq [\frac{x^4}{4^4}\times \frac{y^{3}}{3^3}\times \frac{z^2}{2^2}]^{\frac{1}{9}}}\)

\(1\geq [\frac{x^4}{4^4}\times \frac{y^{3}}{3^3}\times \frac{z^2}{2^2}]^{\frac{1}{9}}\)

\(\huge{\boxed{x^{4}y^{3}z^{2}\leq 4^4 \times 3^3 \times 2^2}}\)

Is this the answer?? – Tanishq Varshney · 2 years, 1 month ago

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This is very Elementary and standard Questions ... It is twisted application of AM-GM ... Known as Weighted AM-GM inequality .

You Can Learn This from Here , wiki Page Airthmetic mean and geometric mean inequality – Karan Shekhawat · 2 years, 1 month ago

@Karan Shekhawat – The other page that I would suggest is Applying AM-GM, which contains detailed explanations and scenarios for further applications. – Calvin Lin Staff · 2 years, 1 month ago

@Calvin Lin – Thanks! – Archit Boobna · 2 years, 1 month ago

@Karan Shekhawat – Thanks so much, its an amazing wiki – Archit Boobna · 2 years, 1 month ago

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## Comments

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TopNewest\(\frac{4x}{4}+\frac{3y}{3}+\frac{2z}{2}=9\)

Applying concept of weighted means

\(\huge{\frac{4\times \frac{x}{4}+3\times \frac{y}{3}+2\times \frac{z}{2}}{4+3+2}\geq [(\frac{x}{4})^{4}\times (\frac{y}{3})^{3}\times (\frac{z}{2})^{2}]^{\frac{1}{4+3+2}}}\)

\(\large{\frac{x+y+z}{9} \geq [\frac{x^4}{4^4}\times \frac{y^{3}}{3^3}\times \frac{z^2}{2^2}]^{\frac{1}{9}}}\)

\(1\geq [\frac{x^4}{4^4}\times \frac{y^{3}}{3^3}\times \frac{z^2}{2^2}]^{\frac{1}{9}}\)

\(\huge{\boxed{x^{4}y^{3}z^{2}\leq 4^4 \times 3^3 \times 2^2}}\)

Is this the answer?? – Tanishq Varshney · 2 years, 1 month ago

Log in to reply

This is very Elementary and standard Questions ... It is twisted application of AM-GM ... Known as Weighted AM-GM inequality .

You Can Learn This from Here , wiki Page Airthmetic mean and geometric mean inequality – Karan Shekhawat · 2 years, 1 month ago

Log in to reply

Applying AM-GM, which contains detailed explanations and scenarios for further applications. – Calvin Lin Staff · 2 years, 1 month ago

The other page that I would suggest isLog in to reply

– Archit Boobna · 2 years, 1 month ago

Thanks!Log in to reply

– Archit Boobna · 2 years, 1 month ago

Thanks so much, its an amazing wikiLog in to reply