GNU Free Documentation License . .

: ,

  , x,   y.

f:\R\to\R, \R\times\R.

, () f:X\to Y

\Gamma_f=\{(x,f(x))\in X\times Y|x\in X\}.

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  • f(x)=\left\{\begin{matrix} a, & x=1 \\ d, & x=2 \\ c, & x=3. \end{matrix}\right.
{(1,a), (2,d), (3,c)}.
f(x)={{x^3}-9x} \!\
  • f(x)={{x^3}-9x}
\{(x, x^3-9 x)\in \R^2\ | x\in\R\}.

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