How to center an equation in Latex? By default my equations are at left side. I’ve searched a lot but none worked. Codes like \begin{center}…\end{center} seem can’t be recognized.

This may be a little late for you, but this is what I usually do.

To align equations to the right

```
\begin{align*}
\bm z^{[1]} = W^{[1]}x + b^{[1]} \\
\bm a^{[1]} = g^{[1]}(\bm z^{[1]}) \\
\end{align*}
```

To align equations to the left, put an `&`

before each line

```
\begin{align*}
& \bm z^{[1]} = W^{[1]}x + b^{[1]} \\
& \bm a^{[1]} = g^{[1]}(\bm z^{[1]}) \\
\end{align*}
```

If you want to numerate the equations (a number will appear after each equation), then delete the `*`

in the `begin`

and `end`

clauses

```
\begin{align}
& \bm z^{[1]} = W^{[1]}x + b^{[1]} \\
& \bm a^{[1]} = g^{[1]}(\bm z^{[1]}) \\
\end{align}
```