這篇是用來測試文章長度會不會影響背景
finish
When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are
$$x = {-b \pm \sqrt{b^2-4ac} \over 2a}.$$
\[ f(n) = \begin{cases} n/2, & \text{if $n$ is even} \\ 3n+1, & \text{if $n$ is odd} \\ \end{cases} \]
\[h_{3}(w)=w_{0}x^{0}+w_{1}x^{1}+w_{2}x^{2}+w_{3}x^{3}\]
