因为网站原因无法上传原图。
我用很笨的方法尝试了很多次大概画了出来。
一下式代码：不知道有没有更好的办法？
\documentclass{standalone}
\usepackage{tikz,amsmath}
\usetikzlibrary{arrows.meta}
\begin{document}
\begin{tikzpicture}
\draw [thick,-Latex] (-1,0)—(7,0) node [below] {\large $x$};
\draw [thick,-Latex] (0,-1)—(0,4.5) node [left] {\large $y$};
\coordinate (start) at (0.8,4);
\coordinate (end) at (6,1);
\draw [thick,smooth] (start) .. controls (1.4,0.5) and (1.6,0.5) .. (2.55,2.4) ..controls (3.5,4.2) and (4.2,4.2) .. (end) ;
\draw [thick,domain=3:6] plot (\x,{-(\x-7.7)});
\node [below left] at (0,0) {$O$};
\draw [densely dashed,thick] (4.5,0)—(4.5,3.2);
\node [above] at (4.6,3.2) {$P$};
\node [below] at (4.5,0) {$5$};
\node at (6,2.8) {$y=-x+8$};
\end{tikzpicture}
\end{document}
