\documentclass{standalone}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{fourier}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}
\usepgfplotslibrary{fillbetween}
\usetikzlibrary{patterns.meta}

\begin{document}

\begin{tikzpicture}
\begin{axis}[
  axis lines=center, 
  axis equal,
  xlabel=$x$, 
  ylabel=$y$,
  domain=-3:5,
  ymin=-3,
  ymax=4.4, 
  xmin=-3.4, 
  xmax=5.4, 
  label style={font=\scriptsize},
  tick label style={font=\scriptsize},
  xtick distance=1,
  ytick distance=1,
  fun/.style={thick, samples=80, smooth}
]

\addplot[name path=f1, fun] {-(x^3)/4+x^2+x/4+0.5};
\addplot[name path=f2, fun, gray] {sin(deg(x))*cos(deg(x))*(2*x)/3+1.4};
\addplot[fill=none] fill between [of=f1 and f2, 
  split,
  every segment no 1/.style={pattern={Lines[angle=45,distance=2pt]}, pattern color=gray},
  every segment no 2/.style={pattern={Lines[angle=-45,distance=2pt]}, pattern color=gray},
];
\end{axis}
\end{tikzpicture}

\end{document}