如何在 https://render.githubusercontent.com 为 github 页生成的等式中显示 + 符号?

How to show the + symbol in an equation that is generated by https://render.githubusercontent.com for github-pages?

我似乎无法让“+”符号出现:

<img src="https://render.githubusercontent.com/render/math?math={\color{black} \large \sigma = f(\mu) = a\mu^2 + b\mu + c} ">   Eqn(2)

它给我这个 wrong result. The appearance I desire is this correct appearance。

这里引用@Jishan 的评论answer

Anyone using this method, because + is an escape character in URI, use %2B to render +.