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All possible values of k
Ecrin_eren   2
N 2 hours ago by DAVROS


The roots of the polynomial
x³ - 2x² - 11x + k
are r₁, r₂, and r₃.

Given that
r₁ + 2r₂ + 3r₃ = 0,
what is the product of all possible values of k?

2 replies
Ecrin_eren
Yesterday at 8:42 AM
DAVROS
2 hours ago
Floor and exact value
Ecrin_eren   3
N 3 hours ago by cowstalker
The exact value of a real number a is denoted by [a] and
the fractional value {a}.
For example; [3.7]= 3 and {3, 7} = 0.7
For a positive real number x,
Given the equality of [x]{x} = 2023, what can
[X^2]-[x]^2 be?
3 replies
Ecrin_eren
Yesterday at 5:54 PM
cowstalker
3 hours ago
Calculating combinatorial numbers
lgx57   7
N 3 hours ago by anduran
Try to simplify this expression:

$$\sum_{i=1}^n \sum_{j=1}^i C_{n}^i C_{n}^j$$
7 replies
lgx57
Mar 30, 2025
anduran
3 hours ago
Inequalities
sqing   0
4 hours ago
Let $ a,b,c\geq 0 ,a+b+c =4. $ Prove that
$$2a +ab +ab^2c \leq\frac{63+5\sqrt 5}{8}$$$$2a +ab^2 +abc \leq \frac{4(68+5\sqrt {10})}{27}$$$$     2a +a^2b + a b^2c^3\leq \frac{4(50+11\sqrt {22})}{27}$$
0 replies
sqing
4 hours ago
0 replies
Inequalities
toanrathay   0
4 hours ago
Let \( a, b, c > 0 \) such that $2(b^2 + bc + c^2) = 1 - 3a^2,$ prove that
\[
a + b + c + \frac{1}{a} + \frac{1}{b} + \frac{1}{c} \geq 10.
\]


0 replies
toanrathay
4 hours ago
0 replies
Find the functions
Ecrin_eren   7
N Today at 12:07 AM by jasperE3
"Find all differentiable functions f that satisfy the condition f(x) + f(y) = f((x + y) / (1 - xy)) for all x, y ∈ R, where xy ≠ 1."
7 replies
Ecrin_eren
Thursday at 8:58 PM
jasperE3
Today at 12:07 AM
2025 CMIMC team p7, rephrased
scannose   12
N Yesterday at 11:36 PM by lpieleanu
In the expansion of $(x^2 + x + 1)^{2024}$, find the number of terms with coefficient divisible by $3$.
12 replies
scannose
Apr 18, 2025
lpieleanu
Yesterday at 11:36 PM
Floor function
Ecrin_eren   1
N Yesterday at 9:38 PM by alexheinis

How many different reel value of a are there which satisfies the equation floor(a) [a-floor(a)]=2024a ?
1 reply
Ecrin_eren
Yesterday at 5:38 PM
alexheinis
Yesterday at 9:38 PM
Maximum value
Ecrin_eren   3
N Yesterday at 6:27 PM by Royal_mhyasd
a,b,c are positive real numbers such that
(a+b)^2 (a+c)^2=16abc
What is the maximum value of a+b+c
3 replies
Ecrin_eren
Yesterday at 1:30 PM
Royal_mhyasd
Yesterday at 6:27 PM
How many pairs
Ecrin_eren   1
N Yesterday at 5:26 PM by Ecrin_eren


Let n be a natural number and p be a prime number. How many different pairs (n, p) satisfy the equation:

p + 2^p + 3 = n^2 ?



1 reply
Ecrin_eren
Yesterday at 3:08 PM
Ecrin_eren
Yesterday at 5:26 PM
Computational polynomial
kamatadu   5
N Jan 12, 2025 by S_14159
Source: STEMS 2023 Maths CAT A Part A P5
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 $pq$?
5 replies
kamatadu
Jan 8, 2023
S_14159
Jan 12, 2025
Computational polynomial
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G H BBookmark kLocked kLocked NReply
Source: STEMS 2023 Maths CAT A Part A P5
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kamatadu
480 posts
#1 • 3 Y
Y by HoripodoKrishno, Rounak_iitr, Mango247
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 $pq$?
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starchan
1606 posts
#2
Y by
Some work shows that if $t$ is a root of $P(x)-1/2$ then so is $1-t$. Since $\deg P$ is odd, this forces one root of $P(x)-1/2$ to be $1/2$ and the others can be paired up into roots summing to one. Thus sum of roots is $2023/2$ and answer is $4046$.
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pco
23508 posts
#3 • 2 Y
Y by StarLex1, Mango247
kamatadu wrote:
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 $pq$?
Other method :
Since polynomial, this implies $P(x)+P(1-x)=1$ $\forall x$

Let $P(x)=ax^{2023}+bx^{2022}+... $ (with $a\ne 0$)

Coefficient pf $x^{2022}$ in $P(x)+P(1-x)$ is $2023a+2b$ and must be zero and so $-\frac ba=\frac{2023}2$

Hence result $\boxed{4046}$
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chakrabortyahan
380 posts
#4
Y by
This problem resembles with some old USATST
$P(x)+P(1-x)-1 = Q(x) $ now note that $Q$ is a zero poly.
So , $P(x)+P(1-x) \equiv 1 $
now let the roots of $P$ be $\alpha_ i $ so the roots of $P(x)=1 $ are also $(1-\alpha_i)$s .Summing we get $\text{sum of the roots}= \frac{2003}{2}$
This post has been edited 1 time. Last edited by chakrabortyahan, Jan 8, 2023, 3:49 PM
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lifeismathematics
1188 posts
#5
Y by
nice
This post has been edited 1 time. Last edited by lifeismathematics, Jan 11, 2023, 3:51 AM
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S_14159
48 posts
#6
Y by
It is easy to see that $P(x)+P(1-x)=1$, taking $P(x)=\sum_{i=0}^{2023}a_{i}x^{i}$ we see that coefficient of $x^{2022}$ is $2023 a+2b=0$ which basically gives us $\boxed{\frac{-b}{a}=\frac{2023}{2}}$
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