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AoPS Volume 2, Problem 262
Shiyul   11
N 6 hours ago by Shiyul
Given that $\color[rgb]{0.35,0.35,0.35}v_1=2$, $\color[rgb]{0.35,0.35,0.35}v_2=4$ and $\color[rgb]{0.35,0.35,0.35} v_{n+1}=3v_n-v_{n-1}$, prove that $\color[rgb]{0.35,0.35,0.35}v_n=2F_{2n-1}$, where the terms $\color[rgb]{0.35,0.35,0.35}F_n$ are the Fibonacci numbers.

Can anyone give me hint on how to solve this (not solve the full problem). I'm not sure how to relate the v series to the Fibonacci sequence.

11 replies
Shiyul
Yesterday at 4:22 AM
Shiyul
6 hours ago
Inequality
math2000   6
N Today at 4:05 AM by sqing
Let $a,b,c>0$.Prove that $\dfrac{1}{(a+b)\sqrt{(a+2c)(b+2c)}}>\dfrac{3}{2(a+b+c)^2}$
6 replies
math2000
Jan 22, 2021
sqing
Today at 4:05 AM
Hard number theory
td12345   3
N Today at 2:51 AM by mathprodigy2011
Let $q$ be a prime number. Define the set
\[
M_q = \left\{ x \in \mathbb{Z}^* \,\middle|\, \sqrt{x^2 + 2q^{2025} x} \in \mathbb{Q} \right\}. 
\]
Find the number of elements of \(M_2  \cup M_{2027}\).
3 replies
td12345
Yesterday at 11:32 PM
mathprodigy2011
Today at 2:51 AM
A complicated fraction
nsato   28
N Today at 1:24 AM by Soupboy0
Compute
\[ \frac{(10^4+324)(22^4+324)(34^4+324)(46^4+324)(58^4+324)}{(4^4+324)(16^4+324)(28^4+324)(40^4+324)(52^4+324)}. \]
28 replies
nsato
Mar 16, 2006
Soupboy0
Today at 1:24 AM
Hardest Computational Problem?
happypi31415   1
N Today at 12:03 AM by mathprodigy2011
What do you guys think the hardest computational problem (for high school students) is?
1 reply
happypi31415
Yesterday at 11:06 PM
mathprodigy2011
Today at 12:03 AM
No bash for this inequality
giangtruong13   2
N Yesterday at 11:30 PM by giangtruong13
Let $x,y,z$ be positive real number satisfy that: $\frac{1}{x^2}+\frac{1}{y^2}+\frac{1}{z^2}=1$.Find the minimum: $$ \sum_{cyc} \frac{(xy)^2}{z(x^2+y^2)} $$
2 replies
giangtruong13
Tuesday at 3:08 PM
giangtruong13
Yesterday at 11:30 PM
Question abt directed angles
idk12345678   6
N Yesterday at 10:16 PM by idk12345678
If you have a diameter of a circle COA, and there is a point on the circle B, then how do you prove CBA is 90 degrees. Usually, i would use the inscribed angle theorem, but you cant divide directed angles by 2
6 replies
idk12345678
Yesterday at 9:09 PM
idk12345678
Yesterday at 10:16 PM
junior 3 and 4 var ineq (2019 Romanian NMO grade VII P1)
parmenides51   8
N Yesterday at 7:44 PM by Burak0609
a) Prove that for $x,y \ge 1$, holds $$x+y - \frac{1}{x}- \frac{1}{y} \ge 2\sqrt{xy} -\frac{2}{\sqrt{xy}}$$
b) Prove that for $a,b,c,d \ge 1$ with $abcd=16$ , holds $$a+b+c+d-\frac{1}{a}-\frac{1}{b}-\frac{1}{c}-\frac{1}{d}\ge 6$$
8 replies
parmenides51
Sep 4, 2024
Burak0609
Yesterday at 7:44 PM
lcm(1,2,3,...,n)
lgx57   2
N Yesterday at 7:09 PM by aidan0626
Let $M=\operatorname{lcm}(1,2,3,\cdots,n)$.Estimate the range of $M$.
2 replies
lgx57
Yesterday at 7:41 AM
aidan0626
Yesterday at 7:09 PM
Random Question
JerryZYang   3
N Yesterday at 7:01 PM by JerryZYang
Can anyone help me prove $\lim_{x\rightarrow\infty}(1+\dfrac{1}{x})^x=\sum_{n=0}^{\infty}\dfrac{1}{n!}$?
3 replies
JerryZYang
Yesterday at 5:03 PM
JerryZYang
Yesterday at 7:01 PM
a