User:Johnxyz1

Revision as of 16:06, 6 September 2024 by Johnxyz1 (talk | contribs)

Favorite topic: \[\text{Counting \& Probability}\]for which I am reading AOPS intermediate book on

Favorite color: \[\text{\textcolor{green}{Green}}\]

Favorite software: \[MS\ \text{Excel}\]

Favorite Typesetting Software: \[\text{\LaTeX}\]

Favorite Operating System: Linux (although I am rarely on one)

Below are some stuff I am doing to practice $\text{\LaTeX}$. That does not mean I know all of it (actually the only ones I do not know yet is the cubic one and the $e^{i\pi}$ one)

\[\text{If }ax^2+bx+c=0\text{, then }x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}\] \[e^{i\pi}+1=0\] \[\sum_{x=1}^{\infty} \frac{1}{x}=2\] \begin{align*} x &= \sqrt[3]{\left(\frac{-b^3}{27a^3} + \frac{bc}{6a^2} - \frac{d}{2a}\right) + \sqrt{\left(\frac{-b^3}{27a^3} + \frac{bc}{6a^2} - \frac{d}{2a}\right)^2 + \left(\frac{c}{3a} - \frac{b^2}{9a^2}\right)^3}} \\ & + \sqrt[3]{\left(\frac{-b^3}{27a^3} + \frac{bc}{6a^2} - \frac{d}{2a}\right) - \sqrt{\left(\frac{-b^3}{27a^3} + \frac{bc}{6a^2} - \frac{d}{2a}\right)^2 + \left(\frac{c}{3a} - \frac{b^2}{9a^2}\right)^3}} - \frac{b}{3a} \\ &\text{(I copied it from another website but I typeset it myself;}\\ &\text{I am pretty sure those are not copyrightable. I still need \textit{years} to even understand this.)}\\ &\text{This is the cubic formula, although it is \textit{rarely} actually used and memorized a lot. The equation is}\\ &ax^3+bx^2+cx+d=0 \end{align*}


Source code for equations:

https://1drv.ms/t/c/c49430eefdbfaa19/EQw12iwklslElg9_nCMh0f0BVthxSSl-BOJAwsXtGbbhPg?e=1LfZJm



Asymptote test (with autoGraph):

[asy]/* AUTO-GRAPH V-4 beta by PythonNut*/  /* Customizations: feel free to edit */ import math; import graph; /* x maximum and minimum */ int X_max = 10; int X_min =-10; /* y maximum and minimum */ int Y_max = 10; int Y_min = -10; /* linewidth */ real line_width = 0.75; /* graph color */ pen graph_color = magenta; /* special */ bool mark_lattice = false; bool show_grid = true; real X_tick_density = 1; real Y_tick_density = 1; real ratio = 1; real resolution = 0.0001; int size = 300; /* graph function */ real f(real x)    {    return sin(x)*sin(x); /* type function to be graphed here */ }  /* The Code. Do not disturb unless you know what you are doing */ bool ib(real t){ return (Y_min <= f(t) && f(t) <= Y_max); }  size(size);unitsize(size*ratio,size);Label l;l.p=fontsize(6); xaxis("$x$",X_min,X_max,Ticks(l,X_tick_density,(X_tick_density/2),NoZero),Arrows); yaxis("$y$",Y_min,Y_max,Ticks(l,Y_tick_density,(Y_tick_density/2),NoZero),Arrows);// if (show_grid){add(shift(X_min,Y_min)*grid(X_max-X_min,Y_max-Y_min));}  real t, T1, T2;  for (T1 = X_min ; T1 <= X_max ; T1 += resolution){     while (! ib(T1) && T1 <= X_max){T1 += resolution;}     if(T1 > X_max){break;}     T2 = T1;      while (  ib(T1) && T1 <= X_max){T1 += resolution;}     T1 -= resolution;     draw(graph(f,T2,T1,n=2400),graph_color+linewidth(line_width),Arrows); }  if (mark_lattice){     for (t = X_min; t <= X_max; ++t){         if (f(t)%1==0 && ib(t)){             dot((t,f(t)),graph_color+linewidth(line_width*4));         }     } } dot((0,0));[/asy]


If you want to typeset your own LaTeX equation in a STANDALONE PDF like AOPS does (although they do images), use the standalone documentclass.


Miscellaneous

On an AMC 8, you can use a ruler to measure things out. Sometimes that works!

Complementary casework example: https://artofproblemsolving.com/wiki/index.php/2024_AMC_8_Problems/Problem_25

Representing Actions as Permutations

The idea is that if you must do a fixed number of operations of multiple types, you can make those operations letters, and permutate them. For example, if you have a grid of 4×6 and you want to walk from one corner to the opposite one, WLOG you need to go up 4 times and right 6 times. You can do that in any order, so basically you are arranging

   UUUURRRRRR

which simplifies the problem.

Example: 2024 AMC 8 Problems/Problem 13. In this problem you can treat going up as U and going down as D. Since you have to end up on the ground in 6 steps you have 3 U's and 3 D's; same as above.