Testing MathJax

Following the instructions here, MathJax works on Blogpost.
I typed

$\cos^2\theta-\sin^2\theta=\cos 2\theta$

and here's the result: $\cos^2\theta-\sin^2\theta=\cos 2\theta$
Antoher equation: $$ax+\frac{b}{y}=1$$ This time, the equation is in display mode.
How about the inline verbatim environment? Googling "mathjax verbatim", we have $$\verb*$x^2\sqrt y$* \text{ yields } x^2\sqrt y$$ on $\rm \TeX \text{ Commands available in MathJax}$ . Nevertheless, it only works in display mode.
Finally, let's get some equations numbered, just like an example on MathJax. $$\begin{equation} \int_{0}^{\frac{\pi}{2}} \sin x \, \mathrm d x = 1 \end{equation}$$