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 $