Use TikZ and PGFPlots keys to keep code DRY

graphs.tex

% https://www.reddit.com/r/LaTeX/comments/1imkst5/tasty_tikz/
\documentclass{article}  
\usepackage{amsmath}% \dfrac
\usepackage{tikz}
\input{svgnam.def}
\pagecolor[HTML]{2A3133}
\color{white}
\usepackage{pgfplots}

% define colors
\definecolor{c1}{HTML}{E035EB}
\definecolor{c2}{HTML}{73E7E5}
\definecolor{c3}{HTML}{F9FB64}

% replace commands with styles
% and use the PGFPLOTS `every *` keys 
\pgfplotsset{
    compat=1.18,
    shape focus/.style={
      axis lines=middle,
      axis line style=dashed,
      xticklabels={},
      yticklabels={},
      xtick={},
      ytick={}    
    },
    every axis/.append style={
        width=0.4\linewidth,% now you don't need to scale the entire picture
        shape focus,
        xmin=-5, xmax=5,
        ymin=-5, ymax=5,
        clip=false,
        axis line style={white},
        every axis title/.append style={font=\scriptsize},
        every axis plot/.append style={
        	<->,line width=1pt,smooth,
    		every node/.append style={below right,midway,font=\scriptsize}
        }
    },
}

\begin{document}


\section*{Basic functions}
\begin{center}
    \renewcommand{\arraystretch}{2}
    \begin{tabular}{ccc}
        \begin{tikzpicture}%linear
            \begin{axis}[c2,title={Identity}]
                \addplot[sharp plot] coordinates {(-3,-3) (3,3)} node {$f(x)=x$};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%square
            \begin{axis}[c1,title={Squaring}]
                \addplot[domain=-2:2]{x^2} node {$f(x)=x^2$};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%cube
            \begin{axis}[c3,title={Cubing}]
                \addplot[domain=-1.5:1.5]{x^3} node {$f(x)=x^3$};
            \end{axis}
        \end{tikzpicture} \\
        \begin{tikzpicture}%absolute
            \begin{axis}[c1,title={Absolute Value}]
                \addplot[<-] coordinates {(-3,3) (0,0)} 
                    node[at end]{$f(x)=|x|$};
                \addplot[->] coordinates {(0,0) (3,3)};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%squareroot
            \begin{axis}[c3,title={Square Root}]
                \addplot[->,domain=0:2] (x^2,x)% helps with the vertical tangent
                    node[at start]{$f(x)=\sqrt{x}$};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%cuberoot
            \begin{axis}[c2,title={Cube Root}]
                \addplot[domain=-1.5:1.5] (x^3,x)% helps with the vertical tangent
                	node {$f(x)=\sqrt[3]{x}$};
            \end{axis}
        \end{tikzpicture} \\
        \begin{tikzpicture}%greatest integer
            \begin{axis}[c3,title={Greatest Integer},
               mark size=1pt
            ]
            	\addplot[arrows={-},jump mark left,mark=*] 
	                coordinates {(-4,-4) (-3,-3) (-2,-2) (-1,-1) (0,0) (1,1) (2,2) (3,3) (4,4)};
	            \addplot[only marks, mark=*,mark options={fill=white}]
	            	coordinates {(-3,-4) (-2,-3) (-1,-2) ( 0,-1) (1,0) (2,1) (3,2) (4,3)}
                    node[pos=0.45] {$f(x) = \lfloor x \rfloor $};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%reciprocal
            \begin{axis}[c2,title={Reciprocal}]
                \addplot[domain=-5:-0.2] {1/x}
                    node[above right, pos=0.7]{$f(x)=\dfrac{1}{x}$};
                \addplot[domain=0.2:5] {1/x};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%exponential
            \begin{axis}[c1,title={Exponential}]
                \addplot[domain=-5:2.2]{2^x}
                    node[near end] {$f(x)=a^x$};
            \end{axis}
        \end{tikzpicture} \\
        \begin{tikzpicture}%sine
            \begin{axis}[c2,title={Sine}]
                \addplot[domain=-4:4]{2*sin(deg(2*x))}
                    node[below,pos=0.8]{$f(x)=\sin x$};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%cosine
            \begin{axis}[c1,title={Cosine}]
                \addplot[domain=-4:4]{2*cos(deg(2*x))}
                    node[below,pos=0.7]{$f(x)=\cos x$};
            \end{axis}
        \end{tikzpicture} &
        \begin{tikzpicture}%tangent
            \begin{axis}[c3,title={Tangent},
                xmin=-360,xmax=360,ymin=-12,ymax=12]
                \addplot[domain=-265:-95] {tan(x)};
                \addplot[domain=95:265]   {tan(x)}
                    node[pos=0.2,anchor=north west]  {\rlap{$f(x)=\tan x$}};
                \addplot[domain=-85:85]   {tan(x)};
            \end{axis}
        \end{tikzpicture}
    \end{tabular}
\end{center}


\end{document}