\documentclass[crop,tikz,convert=pdf2svg]{standalone}
\usetikzlibrary{backgrounds}
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\makeatletter
\begin{document}
\begin{tikzpicture}[scale=3,background rectangle/.style={fill=white}, show background rectangle]
	\begin{axis}[
		no markers,
		width=300,
		height=190,
		xmin = -5.1,	xmax = 5.1,
		ymin = -0.025,	ymax = 1.275,
		ytick = {0,0.25,0.5,0.75,1,1.25},
		yticklabels = {\(0\),\(\frac{1}{4}\),\(\frac{1}{2}\),\(\frac{3}{4}\),\(1\),\(1\frac{1}{4}\)},
		domain=-5.5:5.5,
		samples=512,
		xlabel=\(p\),
		ylabel={Intensity}
	]
	\addplot[color=blue] {1/(1+(x+1)^2)};
	\addplot[color=red] {0.5/(1+(x-1)^2)};
	\addplot[color=black] {1/(1+(x+1)^2) + 0.5/(1+(x-1)^2)};
	\end{axis}
\end{tikzpicture}
\end{document}