\begin{tikzpicture}
\begin{axis}[ymax=17,ymin=-1]
\addplot [color=red, domain=-4:4, samples=50]{x^2};
\node[label={180:{(1,5)}},circle,fill,inner sep=1.5pt] at (axis cs:1,5) {};
\addplot [color=black!80, domain=-4:4, samples=50]{(-0.4)*(x+0.2)+(0.2^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{0};
\addplot [color=black!80, domain=-4:4, samples=50]{(2)*(x)-1};
\addplot [color=black!80, domain=-4:4, samples=50]{(-2)*x-1};
\addplot [color=black!80, domain=-4:4, samples=50]{(-3)*(x+1.5)+(1.5^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(3)*(x-1.5)+(1.5^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(-4)*(x+2)+(2^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(4)*(x-2)+(2^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(1.2)*(x-0.6)+(0.6^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(-1.2)*(x+0.6)+(0.6^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(-0.8)*(x+0.4)+(0.4^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(0.8)*(x-0.4)+(0.4^2)};
\addplot [color=black!80, domain=-4:4, samples=50]{(0.4)*(x-0.2)+(0.2^2)};
\end{axis}
\end{tikzpicture}
这就是我所苦苦挣扎的问题,y=x^2 的红色图形位于黑线后面(它们是切线)