实验页

[math]\displaystyle{ \begin{equation} E=mc^2 \label{1} \tag{1} \end{equation} }[/math]

In equation [math]\displaystyle{ \ref{1} }[/math], we find the value of an interesting integral:

[math]\displaystyle{ x \href{why-equal.html}{=} y^2 + 1 (x+1)^2 = \class{hidden}{(x+1)(x+1)} (x+1)^2 = \cssId{step1}{\style{visibility:hidden}{(x+1)(x+1)}} }[/math]