公式
$$
Ф β △ τ αφωψπΩΓεγµσ←↑→θηδ≤≥
$$
$$ x^2 $$
$$ ρ $$
$$
$$
$$\sum_{i=0}N\int_{a}{b}g(t,i)\text{d}t$$
$ J \left ( \theta\right )= \frac{1}{2m}\sum_{i=1}^{m}\left ( h_{\theta }\left ( x^{\left ( i \right )} \right )-y^{\left ( i \right )} \right )^{2} $
