\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usepackage{pgfplots}
\usepackage{filecontents}

\begin{document}
\begin{tikzpicture}
\begin{axis}[axis x line=center,axis y line=center,
xtick ={-8,-7,...,8}, ytick ={-8,-7,...,8},
xlabel ={$x$}, ylabel ={$y$},
xlabel  style ={below  right}, ylabel  style ={right},
xmin=-8.5, xmax =8.5,
ymin=-8.5, ymax =8.5,
title={$f\left( x \right)=x^2-2x+3$}]
\addplot[mark=none ,samples =500, blue, line  width =0.5pt]{x*x-2*x+3};
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[axis x line=center, axis y line=center,
xtick ={-3,-2,...,3}, ytick ={-3,-2,...,3},
xlabel ={$x$}, ylabel ={$y$},
xlabel  style ={below  right}, ylabel  style ={right},
xmin=-3.5, xmax =3.5,
ymin=-3.5, ymax =3.5,
title={$f\left( x \right) =\cos(2x)$}]
\addplot[mark=none ,samples =500, purple, line  width =0.5pt]{cos(deg(2*x))};
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[axis x line=center, axis y line=center,
xtick ={-2,-1,...,2}, ytick ={-2,-1,...,2},
xlabel ={$x$}, ylabel ={$y$},
xlabel  style ={below  right}, ylabel  style ={right},
xmin=-2.5, xmax =2.5,
ymin=-2.5, ymax =2.5,
title={$f\left( x \right) =\sin(\frac{1}{x})$}]
\addplot[mark=none ,samples =500, pink, line  width =0.5pt]{sin(deg(1/x))};
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[title={$f\left( x \right) =x^2+y^2$}]
\addplot3[surf,domain =0:360, samples =50]{x*x+y*y};
\end{axis}
\end{tikzpicture}

\begin{tikzpicture}
\begin{axis}[title={$f\left( x \right) =x^2-y^2+2xy^2+1$}]
\addplot3[surf,domain =0:360, samples =50]{x*x-y*y+2*x*y*y+1};
\end{axis}
\end{tikzpicture}

\newpage
\begin{tikzpicture}
\begin{axis}[axis x line=center, axis y line=center,
xtick ={-5,-4,...,8}, ytick ={-5,-4,...,8},
xlabel ={$x$}, ylabel ={$y$},
xlabel  style ={below  right},ylabel  style ={right},
xmin=-5, xmax =5,
ymin=-2, ymax =8,
title={$x^2-1$}]
\addplot[line width=1pt] gnuplot [raw gnuplot]{plot 'dane.dat' using 1:2};
\end{axis}
\end{tikzpicture}

\end{document}