$show=home

2011 Issue 404

  1. Given seven distinct prime numbers $a$, $b$, $c$, $a+b+c$, $a+b-c$, $a-b+c$, $-a+b+c$ in which the sum of two of three numbers $a$, $b$, $c$ equals $800$. Let $d$ be the difference between the largest and the smallest number among these seven integers. What is the maximum value of $d ?$
  2. A triangle $A B C$ has sides $A B=2cm$, $A C=4cm$ and median $A M=\sqrt{3}cm$. Find the measure of the angle $B A C$, the length of side $B C$ and the area of triangle $A B C$.
  3. Find the largest natural number $k$ so that $n^{5}-2011 n$ is divisible by $k$ for all natural number $n$.
  4. Solve the equation $$\left(x^{4}-625\right)^{2}-100 x^{2}-1=0$$
  5. Let $A B C$ be an acute triangle $(A B \neq A C)$ inscribed in the circle $(O),$ and $H$ is its orthocenter. Let $d$ be an arbitrary line passing through $H$. Draw the line $d^{\prime}$ symmetric to $d$ through $B C$. Find the position of the line $d$ so that $d^{\prime}$ touches the circumcircle $(O)$.
  6. Find the largest constant $k$ such that $$\frac{a^{2}}{b}+\frac{b^{2}}{c}+\frac{c^{2}}{a} \geq k\left(a^{2}+b^{2}+c^{2}\right)$$ for all positive real numbers $a$, $b$, and $c$ whose sum equals $1 .$
  7. Let $A B C$ be a triangle inscribed in the circle $(O)$, and let $G$ be its centroid; $D$, $E$, and $F$ are the circumcenters of triangles $G B C$, $G C A$, $G A B$ respectively. Prove that $O$ is the centroid of $D E F$.
  8. Solve the equation $$\sqrt[3]{\cos 5 x+2 \cos x}-\sqrt[3]{2 \cos 5 x+\cos x}=2 \sqrt[3]{\cos x}(\cos 4 x-\cos 2 x).$$
  9. Let $x$, $y$, $z$ be real numbers such that $x \geq 1$, $y \geq 2$, $z \geq 3$ and $$\frac{1}{x+\sqrt{x-1}}+\frac{2}{y+\sqrt{y-2}}+\frac{3}{z+\sqrt{z-3}}=12$$ Find the maximum and minimum value of the function $f(x, y, z)=x+y+z$.
  10. Let $\left(x_{n}\right)$ be a sequence given by $$x_{1}=\frac{5}{2},\quad x_{n+1}=\sqrt{x_{n}^{3}-12 x_{n}+\frac{20 n+21}{n+1}},\,\forall n \in \mathbb{N}^{*}.$$ Prove that the sequence $\left(x_{n}\right)$ converges and find its limit.
  11. Find all functions $f: \mathbb{R} \rightarrow(0 ; 2011]$ such that $$f(x) \leq 2011\left(2-\frac{2011}{f(y)}\right),\,\forall x>y.$$
  12. Given four points $A_{I}$ $(i=1,2,3,4),$ no three of them are colinear and a point $M$ so that $A_{i}$ $(i=1,2,3,4)$ and $M$ do not lie on the same circle. Let $T_{i}$ be a triangle having $A_{j}$ $(j=1,2,3,4 ; j \neq i)$ as its vertices, $C_{i}$ is the circle (or the line) passing through the feet of the projections through $M$ onto three sides (or extended sides) of triangle $T_{i}$. Prove that $C_{I}$ $(i=1,2,3,4)$ have a common point.

$type=three$c=3$source=random$title=oot$p=1$h=1$m=hide$rm=hide

Anniversary_$type=three$c=12$title=oot$h=1$m=hide$rm=hide

Name

2006,1,2007,12,2008,12,2009,12,2010,12,2011,12,2012,12,2013,12,2014,12,2015,12,2016,12,2017,12,2018,11,2019,12,2020,12,2021,4,Anniversary,4,
ltr
item
Mathematics & Youth: 2011 Issue 404
2011 Issue 404
Mathematics & Youth
https://www.molympiad.org/2020/09/2011-issue-404.html
https://www.molympiad.org/
https://www.molympiad.org/
https://www.molympiad.org/2020/09/2011-issue-404.html
true
8958236740350800740
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS CONTENT IS PREMIUM Please share to unlock Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy