Text alignment between curly braces

Question

I am trying to rewrite an equation that looks like this:

The latex code I have written so far is:

\documentclass{article}
\begin{document}
[f(x,\alpha,x_m) = \biggl{ \frac {\alpha x_m^\alpha} {x_i^{\alpha + 1}},  x \ge x_m ]
\end{document}

Which gives the following compilation:

How do I align the rest of the values I need as shown in the first pic.

Answer 1

Use a cases environment if the material to the right of the tall curly brace should be typeset in text-style math mode, and a dcases environment if the material should be typeset in display-style math mode.

\documentclass{article}
\usepackage{mathtools} % for 'dcases' environment
\begin{document}
\begin{align}
f(x,\alpha,x_m) &=

\begin{cases} 
\frac {\alpha x_m^\alpha} {x_i^{\alpha + 1}} & \text{if $x\ge x_m$} \
0 & \text{otherwise}
\end{cases} \[2ex]
f(x,\alpha,x_m) &=

\begin{dcases} 
\frac {\alpha x_m^\alpha} {x_i^{\alpha + 1}} & \text{if $x\ge x_m$} \
0 & \text{otherwise}
\end{dcases}
\end{align}
\end{document}