数学公式的输入

 

<img src="http://latex.codecogs.com/gif.latex?\int_{-\infty}^\infty e^{-x^2}dx=\sqrt{\pi}" title="" alt="" />

    

<img src="http://latex.codecogs.com/gif.latex?\sqrt{a^2+b^2}" title="\sqrt{a^2+b^2}" />

<img src="http://www.imathas.com/cgi-bin/mimetex.cgi?\blue\large\displaystyle f(x)=\int_{-\infty}^xe^{-t^2}dt" alt="" />

<img src="http://www.imathas.com/cgi-bin/mimetex.cgi?\red\large\displaystyle f(x)=\int_{-\infty}^xe^{-t^2}dt" alt="" />