1.
, .
, , , , , , .
.
, - . , , , ..
, . .
x X, x ∈ (∈ ).
, ⊂ (⊂ ).
: .
, :
- ={1,2,3,5,7}
- ={x1,x2,...,xn} x1,x2,...,xn
- N={1,2,...,n}
- Z={0,1,2,...,n}
(-∞;+∞) , . a δ . (a-δ; a+δ) δ- .
(), c, x ∈ X x≤ (x≥c). () . , , . () () () .
N | {1,2,3,...,n} |
Z | {0, 1, 2, 3,...} . . |
Q | . . , p , q . . : 0,25 = 25/100 = 1/4. . , "": 2 = 2/1. . |
R | .
. :
|
, Ø.