# Left-align math and also align by equal sign?

The `fl`

in `flalign`

and `flalign*`

is short for "full length", *not* "flush left". Please see page 8 of the user guide of the `amsmath`

package for some use cases for `flalign`

. (Aside: Just because `flalign`

*can* be abused to force displayed equations to be typeset left-aligned doesn't mean that it's harmless to do so.)

If the objective is to typeset displayed equations left-aligned rather than centered, you really shouldn't be using `flalign`

. Instead, load the `amsmath`

or `mathtools`

package with the option `fleqn`

(short for "flush-left equations") and set the value of the `\mathindent`

length variable to `0pt`

.

```
\documentclass{article}
\usepackage[fleqn]{amsmath}
\setlength{\mathindent}{0pt}
\usepackage{showframe} % optional
\begin{document}
\begin{align*}
f(x) &= -1.25x^{2} + 1.5x + 1.66 \\
&= -1.25x^{2} + 1.5x + 1.66 + 0 % note: no '\\' at end of final line of 'align'
\end{align*}
\end{document}
```

To align at the `=`

, you need to have the `&`

to be just *before* the `=`

:

##Code:

```
\documentclass{article}
\usepackage{mathtools}
\usepackage{showframe}
\begin{document}
\begin{flalign*}
f(x) &= -1.25x^{2} + 1.5x + 1.66 & \\
&= -1.25x^{2} + 1.5x + 1.66 + 0 & \\
\end{flalign*}
\end{document}
```