Math Test

This is a blog just test math symbol like $ \iiint g(x,y,z)dxdydz $ in markdown.

And the root of equation:

$$ x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} $$

在此引用公示 \eqref{YY} 和 \eqref{XX} .

$$ f(x,y,z) = 3y^2z \left( 3+\frac{7x+5}{1+y^2} \right) $$

$$ \frac{n!}{k!(n-k)!}. $$