This is a new post.
$\frac{1}{2}$ is a Latex thing; don't know if it'll work.
Now let's try the quadratic formula:
$\frac{-b\pm\sqrt{b^2-4ac}}{2a}=x$ is the solution to $ax^2+bx+c$.
A system of equations:
$ax+by=c$
$dx+ey=f$
when
$x=0 and
y=0$
