# multiple single line equations with part of text

I am not able to align them properly.

How can I have multiple line equation, with each equation is labeled properly.

Here is an example:

\documentclass{article}
\usepackage{amsmath} % for 'align*' environment

\begin{document}
\begin{equation} \label{eq:sr}
\mbox{Inductive reactance as:} X_L = 2 \pi f L = \omega L \\
\mbox{Capacitive reactance as:} X_c = \frac{1}{2 \pi f C} = \frac{1}{\omega C} \\
\mbox{Total circuit reactance:} X_T = X_L - X_C or X_C - X_L \\
\mbox{Total circuit impedance:} Z = \sqrt{R^2 + X_T^2} = R + jX \\
\mbox{When} X_L = X_C \rightarrow 2 \pi f L  = \frac{1}{2 \pi f C} \\
f_r = \frac{1}{2 \pi \sqrt{L C}} (Hz) or \omega_r = \frac{1}{L C} (rads) \\
\end{equation}

\end{document}

• instead of equation you should use gather or align ... – Zarko Nov 8 '16 at 8:17

Multiple alignments with enumeration is best achieved with something like alignat from amsmath: \documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{alignat}{2}
\text{Inductive reactance as:}  & \quad & X_L &= 2 \pi f L = \omega L \\
\text{Capacitive reactance as:} &       & X_c &= \frac{1}{2 \pi f C} = \frac{1}{\omega C} \\
\text{Total circuit reactance:} &       & X_T &= X_L - X_C or X_C - X_L \\
\text{Total circuit impedance:} &       &   Z &= \sqrt{R^2 + X_T^2} = R + jX \\
\text{When} &       & X_L &= X_C \rightarrow 2 \pi f L = \frac{1}{2 \pi f C} \\
&       & f_r &= \frac{1}{2 \pi \sqrt{L C}} \text{ (Hz) or }
\omega_r = \frac{1}{L C} \text{ (rads)}
\end{alignat}

\end{document}

• Thanks. Everything is ok, but may I know why you used \quad there ? – cppiscute Nov 8 '16 at 8:38
• May I know how can I disable the label for certain line in the above equation alignment ? – cppiscute Nov 8 '16 at 9:09
• @statisticalbeginner: Insert \nonumber before \\ on the same line. – Werner Nov 8 '16 at 16:12