Olympiad problems

2004 Baltic Way, 2

Let $ P(x)$ be a polynomial with a non-negative coefficients. Prove that if the inequality $ P\left(\frac {1}{x}\right)P(x)\geq 1$ holds for $ x \equal{} 1$, then this inequality holds for each positive $ x$.

2004 India IMO Training Camp, 2

Tags: polynomial , algebra

Let $P(x) = x^4 + ax^3 + bx^2 + cx + d$ and $Q(x) = x^2 + px + q$be two real polynomials. Suppose that there exista an interval $(r,s)$ of length greater than $2$ SUCH THAT BOTH $P(x)$ AND $Q(x)$ ARE nEGATIVE FOR $X \in (r,s)$ and both are positive for $x > s$ and $x<r$. Show that there is a real $x_0$ such that $P(x_0) < Q(x_0)$

2012 Iran MO (3rd Round), 1

Tags: algebra , modular arithmetic , prime number , number theory , polynomial , inequalities

$P(x)$ is a nonzero polynomial with integer coefficients. Prove that there exists infinitely many prime numbers $q$ such that for some natural number $n$, $q|2^n+P(n)$. [i]Proposed by Mohammad Gharakhani[/i]

2009 Indonesia TST, 1

Tags: algebra , number theory , quadratic , polynomial

Find the smallest odd integer $ k$ such that: for every $ 3\minus{}$degree polynomials $ f$ with integer coefficients, if there exist $ k$ integer $ n$ such that $ |f(n)|$ is a prime number, then $ f$ is irreducible in $ \mathbb{Z}[n]$.

2015 VJIMC, 4

Tags: polynomial , number theory

[b]Problem 4 [/b] Let $m$ be a positive integer and let $p$ be a prime divisor of $m$. Suppose that the complex polynomial $a_0 + a_1x + \ldots + a_nx^n$ with $n < \frac{p}{p-1}\varphi(m)$ and $a_n \neq 0$ is divisible by the cyclotomic polynomial $\phi_m(x)$. Prove that there are at least $p$ nonzero coefficients $a_i\ .$ The cyclotomic polynomial $\phi_m(x)$ is the monic polynomial whose roots are the $m$-th primitive complex roots of unity. Euler’s totient function $\varphi(m)$ denotes the number of positive integers less than or equal to $m$ which are coprime to $m$.

1973 Swedish Mathematical Competition, 5

Tags: polynomial , algebra

$f(x)$ is a polynomial of degree $2n$. Show that all polynomials $p(x)$, $q(x)$ of degree at most $n$ such that $f(x)q(x)-p(x)$ has the form \[ \sum\limits_{2n<k\leq 3n} (a^k + x^k) \] have the same $p(x)/q(x)$.

1973 IMO Shortlist, 16

Tags: trigonometry , algebra , polynomial , factorization , geometry

Given $a, \theta \in \mathbb R, m \in \mathbb N$, and $P(x) = x^{2m}- 2|a|^mx^m \cos \theta +a^{2m}$, factorize $P(x)$ as a product of $m$ real quadratic polynomials.

2003 Balkan MO, 1

Tags: polynomial , pigeonhole principle , greatest common divisor , algebra , induction , number theory

Can one find 4004 positive integers such that the sum of any 2003 of them is not divisible by 2003?

1993 Tournament Of Towns, (398) 6

Tags: algebra , inequalities , polynomial

If it is known that the equation $$x^4+ax^3+2x^2+bx+1=0$$ has a (real) root, prove the inequality $$a^2+b^2 \ge 8.$$ (A Egorov)

1999 Hungary-Israel Binational, 1

Tags: inequalities , algebra , polynomial

$ c$ is a positive integer. Consider the following recursive sequence: $ a_1\equal{}c, a_{n\plus{}1}\equal{}ca_{n}\plus{}\sqrt{(c^2\minus{}1)(a_n^2\minus{}1)}$, for all $ n \in N$. Prove that all the terms of the sequence are positive integers.

2000 Estonia National Olympiad, 3

Tags: algebra , polynomial , root , integer

Find all values of $a$ for which the equation $x^3 - x + a = 0$ has three different integer solutions.

2002 SNSB Admission, 3

Tags: polynomial , algebra , topology , quadratic , function

Classify up to homeomorphism the topological spaces of the support of functions that are real quadratic polynoms of three variables and and irreducible over the set of real numbers.

2001 Romania National Olympiad, 4

Tags: polynomial , algebra

Let $n\ge 2$ be an even integer and $a,b$ real numbers such that $b^n=3a+1$. Show that the polynomial $P(X)=(X^2+X+1)^n-X^n-a$ is divisible by $Q(X)=X^3+X^2+X+b$ if and only if $b=1$.

2015 India Regional MathematicaI Olympiad, 3

Tags: polynomial , algebra , integer polynomial , divisibility

Let $P(x)$ be a polynomial whose coefficients are positive integers. If $P(n)$ divides $P(P(n)-2015)$ for every natural number $n$, prove that $P(-2015)=0$. [hide]One additional condition must be given that $P$ is non-constant, which even though is understood.[/hide]

2007 IMC, 2

Tags: algebra , modular arithmetic , polynomial

Let $ x$, $ y$ and $ z$ be integers such that $ S = x^{4}+y^{4}+z^{4}$ is divisible by 29. Show that $ S$ is divisible by $ 29^{4}$.

STEMS 2023 Math Cat A, 5

Tags: polynomial , algebra , computational

Consider a polynomial $P(x) \in \mathbb{R}[x]$, with degree $2023$, such that $P(\sin^2(x))+P(\cos^2(x)) =1$ for all $x \in \mathbb{R}$. If the sum of all roots of $P$ is equal to $\dfrac{p}{q}$ with $p, q$ coprime, then what is the product $pq$?

2009 Germany Team Selection Test, 3

Tags: calculus , polynomial , algebra , function

Find all functions $ f: \mathbb{R} \mapsto \mathbb{R}$ such that $ \forall x,y,z \in \mathbb{R}$ we have: If \[ x^3 \plus{} f(y) \cdot x \plus{} f(z) \equal{} 0,\] then \[ f(x)^3 \plus{} y \cdot f(x) \plus{} z \equal{} 0.\]

2010 IMO Shortlist, 3

Tags: algebra , number theory , polynomial , sum of squares

Find the smallest number $n$ such that there exist polynomials $f_1, f_2, \ldots , f_n$ with rational coefficients satisfying \[x^2+7 = f_1\left(x\right)^2 + f_2\left(x\right)^2 + \ldots + f_n\left(x\right)^2.\] [i]Proposed by Mariusz Skałba, Poland[/i]

2009 Ukraine National Mathematical Olympiad, 4

Tags: algebra , polynomial

Find all polynomials $P(x)$ with real coefficients such that for all pairwise distinct positive integers $x, y, z, t$ with $x^2 + y^2 + z^2 = 2t^2$ and $\gcd(x, y, z, t ) = 1,$ the following equality holds \[2P^2(t ) + 2P(xy + yz + zx) = P^2(x + y + z) .\] [b]Note.[/b] $P^2(k)=\left( P(k) \right)^2.$

India EGMO 2022 TST, 6

Tags: algebra , polynomial

Suppose $P(x)$ is a non-constant polynomial with real coefficients, and even degree. Bob writes the polynomial $P(x)$ on a board. At every step, if the polynomial on the board is $f(x)$, he can replace it with 1. $f(x)+c$ for a real number $c$, or 2. the polynomial $P(f(x))$. Can he always find a finite sequence of steps so the final polynomial on the board has exactly $2020$ real roots? What about $2021$? [i]~Sutanay Bhattacharya[/i]

2022 Harvard-MIT Mathematics Tournament, 6

Tags: algebra , complex number , polynomial

Let $P(x) = x^4 + ax^3 + bx^2 + x$ be a polynomial with four distinct roots that lie on a circle in the complex plane. Prove that $ab\ne 9$.

1987 IMO Longlists, 24

Tags: polynomial , vieta , algebra

Prove that if the equation $x^4 + ax^3 + bx + c = 0$ has all its roots real, then $ab \leq 0.$

Russian TST 2016, P1

Tags: algebra , inequality , polynomial

For which even natural numbers $d{}$ does there exists a constant $\lambda>0$ such that any reduced polynomial $f(x)$ of degree $d{}$ with integer coefficients that does not have real roots satisfies the inequality $f(x) > \lambda$ for all real numbers?

2017 CMIMC Algebra, 10

Tags: polynomial , algebra

Let $c$ denote the largest possible real number such that there exists a nonconstant polynomial $P$ with \[P(z^2)=P(z-c)P(z+c)\] for all $z$. Compute the sum of all values of $P(\tfrac13)$ over all nonconstant polynomials $P$ satisfying the above constraint for this $c$.

1999 Putnam, 2

Tags: algebra , polynomial

Let $p(x)$ be a polynomial that is nonnegative for all real $x$. Prove that for some $k$, there are polynomials $f_1(x),f_2(x),\ldots,f_k(x)$ such that \[p(x)=\sum_{j=1}^k(f_j(x))^2.\]