Olympiad problems

2012 Grigore Moisil Intercounty, 3

Solve in the real numbers the equation $ (n+1)^x+(n+3)^x+\left( n^2+2n\right)^x=n^x+(n+2)^x+\left( n^2+4n+3\right)^x, $ wher $ n\ge 2 $ is a fixed natural number.

monotone algebra

2019 Ramnicean Hope, 1

Solve in the reals the equation $ \sqrt[3]{x^2-3x+4} +\sqrt[3]{-2x+2} +\sqrt[3]{-x^2+5x+2} =2. $ [i]Ovidiu Țâțan[/i]

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2004 Gheorghe Vranceanu, 2

Solve in $ \mathbb{R}^2 $ the following equation. $$ 9^{\sqrt x} +9^{\sqrt{y}} +9^{1/\sqrt{xy}} =\frac{81}{\sqrt{x} +\sqrt{y} +1/\sqrt{xy}} $$ [i]O. Trofin[/i]

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Let be a function satisfying [url=http://mathworld.wolfram.com/CauchyFunctionalEquation.html]Cauchy's functional equation,[/url] and having the property that it's monotonic on a real interval. Prove that this function is globally monotonic. [i]Florian Dumitrel[/i]

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2004 Alexandru Myller, 4

Let be a real function that has the intermediate value property and is monotone on the irrationals. Show that it's continuous. [i]Mihai Piticari[/i]

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2006 Cezar Ivănescu, 1

Solve the equation [b]a)[/b] $ \log_2^2 +(x-1)\log_2 x =6-2x $ in $ \mathbb{R} . $ [b]b)[/b] $ 2^{x+1}+3^{x+1} +2^{1/x^2}+3^{1/x^2}=18 $ in $ (0,\infty ) . $ [i]Cristinel Mortici[/i]

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2005 Grigore Moisil Urziceni, 1

Prove that $ 5^x+6^x\le 4^x+8^x, $ for any nonegative real numbers $ x. $

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