ClearAll["Global`*"];
SetDirectory[NotebookDirectory[]];
$HistoryLength=3;

b + 2, tohle je text

(*komentar*)
b+1+c+α

vyr=(x^3)+b*Sin[x+y];
TreeForm[vyr]
FullForm[vyr];

(x^3)+b*Sin[x+y]=2

(*neco o listech*)
listik={ja,ty,{alfa,romeo},{dub,{sekera}}};
(*vyber prvku*)
listik[[3]][[2]];
listik[[3,2]];
listik[[-2]];
First[listik];
Last[listik];
Length[listik];

?_

ClearAll[f];
f[x:_]:=(x^2);
f[5]

?:=

ClearAll[f];
x=1;
f[x_]:=(x^2)
f[5]
?f

?=

ClearAll[f];
f[x_]=(x^2)
f[5]
?f

f[x_]:=Integrate[(a^2)*Sin[a*x+(x^2)],x];
f[1];

ClearAll[f,x];
f[x_]=Integrate[(a^2)*Sin[a*x+(x^2)],x];
f[0.5]

ClearAll[f];
f[x_]:=x;
f[x_Integer]:=(E/x);
f[1]:=1;
f[1]

ClearAll[a];
a[n_]:=n*a[n-1];
a[0]:=1;
a[5]

a[n_]:=n*a[n-1];
a[0]:=1;

Trace[a[3]];

$RecursionLimit=(10^4);

ClearAll[a];
a[n_]:=n*a[n-1];
a[0]:=1;
Timing[Table[a[i],{i,1000}]][[1]]

ClearAll[a];
a[n_]:=a[n]=n*a[n-1]//N;
a[0]:=1;
Timing[Table[a[i],{i,1000}]][[1]]

ClearAll[f,x];
f[x_]:=-x*(x-2)/;0≤x≤2;
f[x_]:=f[x-2]/;x>2;
f[x_]:=f[x+2]/;x<0;
Plot[f[x],{x,-10,10}];
Trace[f[8.5]];