test latex1

equation systems:
\begin{equation}
1 + 2 = 3 \
1 = 3 - 2
\end{equation}
align text
\begin{align}
1+2 &= 3\newline
f(x) &= x^2\
g(x) &= \frac{1}{x}\
F(x) &= \int^a_b \frac{1}{3}x^3\
\nabla b& = \int x^2dx
\end{align}

center a formula : $$a \nabla b = \int x^2dx $$ end

paragraph
This formula \(f(x) = x^2\) is an example.
$ \nabla b = \int x^2dx $