Left align block of equations - latex

Question

I want to left align a block of equations. The equations in the block itself are aligned, but that's not related at all to my question! I want to left align the equations rather than have them centered all the time, because it looks dumb with narrow centered equations.
Example, I want to left align this
\begin{align*}
|\vec a| &= \sqrt{3^{2}+1^{2}} = \sqrt{10} \\
|\vec b| &= \sqrt{1^{2}+23^{2}} = \sqrt{530} \\
\cos v &= \frac{26}{\sqrt{10} \cdot \sqrt{530}} \\
v &= \cos^{-1} \left(\frac{26}{\sqrt{10} \cdot \sqrt{530}}\right) \\
v &= \uuline{69.08...\degree}
\end{align*}
but also this
\begin{align*}
f(x) = -1.25x^{2} + 1.5x
\end{align*}
How is this done? If it's even possible.

Answer 1

Try to use the fleqn document class option.
\documentclass[fleqn]{article}
(See also http://en.wikibooks.org/wiki/LaTeX/Basics for a list of other options.)

Answer 2

You can use \begin{flalign}, like the example bellow:
\begin{flalign}
&f(x) = -1.25x^{2} + 1.5x&
\end{flalign}

Answer 3

Try this:
\begin{flalign*}
&|\vec a| = \sqrt{3^{2}+1^{2}} = \sqrt{10} & \\
&|\vec b| = \sqrt{1^{2}+23^{2}} = \sqrt{530} &\\
&\cos v = \frac{26}{\sqrt{10} \cdot \sqrt{530}} &\\
&v = \cos^{-1} \left(\frac{26}{\sqrt{10} \cdot \sqrt{530}}\right) &\\
\end{flalign*}
The & sign separates two columns, so an & at the beginning of a line means that the line starts with a blank column.

Answer 4

The fleqn option in the document class will apply left aligning setting in all equations of the document. You can instead use \begin{flalign}. This will align only the desired equations.