Hastebin

\documentclass{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}

\begin{document}

\begin{tikzpicture}
\begin{axis}[xmin=0,xmax=5,ymin=0]

\addplot[blue, thick, name path=curveA] {x^2/4};
\path[name path=xaxis] (axis cs:0,0) -- (axis cs:5,0);
\addplot[blue!40, opacity=0.6] fill between[of=curveA and xaxis];


\addplot[red, thick, name path=curveB] {2*sin(deg(x))+1};
\addplot[red!40, opacity=0.4] fill between[of=curveB and xaxis];

\end{axis}
\end{tikzpicture}

\end{document}