Many formulas are not rendered
$$J(\theta_0, \theta_1) = \dfrac {1}{2m} \displaystyle \sum {i=1}^m \left ( \hat{y}{i}- y_{i} \right)^2 = \dfrac {1}{2m} \displaystyle \sum {i=1}^m \left (h\theta (x_{i}) - y_{i} \right)^2$$
This formula could not be rendered in the following link, and there are much more formulas could not be rendered like this, although it can be rendered in this issue post. https://github.com/scruel/ML-AndrewNg-Notes/blob/master/notes/week1.md#22-%E6%8D%9F%E5%A4%B1%E5%87%BD%E6%95%B0cost-function

$ h_\theta(x) \geqslant 0.5 $ shows error "Undefined control sequence \geqslant"
\geqslant is defined by MathJax extension AMSsymbol [1], and it can be loaded by [2]
TeX: {
extensions: ["AMSmath.js", "AMSsymbols.js"]
}
However, github-mathjax does not load any MathJax TeX extensions. Hence \geqslant is undefined.
https://github.com/orsharir/github-mathjax/blob/d73c97dd2643d53e6b0bde3a721eb13913b64524/mathjax_config.js#L11
[1] http://docs.mathjax.org/en/latest/tex.html#g
[2] MathJax doc - How to load extension AMSsymbol
@muzimuzhi Thanks! This works for me.