How to set some lines right aligned in the align enviroments?

I have try some code like this:

\begin{align*}
Q(R)&=\bi(R,R)\\
&=\bi(R_I+R_{\Rico}+R_W,R_I+R_{\Rico}+R_W)\\
&=\bi(R_I,R_I)+2\bi(R_I,R_{\Rico})+2\bi(R_I,R_W)\\
&+\bi(R_{\Rico},R_{\Rico})+2\bi(R_{\Rico},R_w)\\
&+\bi(R_W,R_W).
\end{align*}


where

\newcommand{\Rico}{\Ric_o}
\newcommand{\bi}{\mathrm{bi}\,}


The problem is I would like to set the last three lines aligned right, did there has any solutions instead to type several \quad or \qquad?

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maybe \hspace will be a solution. –  user19832 Dec 3 '12 at 14:34

2 Answers

I would place the last three equations in an extra aligned environment as follows:

\documentclass{article}

\usepackage{mathtools}

\DeclareMathOperator{\Ric}{Ric}
\newcommand{\Rico}{\Ric_o}
\DeclareMathOperator{\bi}{bi}

\begin{document}
\begin{align*}
Q(R) ={}&\bi(R,R)\\
={}&\bi(R_I+R_{\Rico}+R_W,R_I+R_{\Rico}+R_W)\\
={}&\begin{aligned}[t]
\bi(R_I,R_I)+2\bi(R_I,R_{\Rico})+2\bi(R_I,R_W)&\\
+\bi(R_{\Rico},R_{\Rico})+2\bi(R_{\Rico},R_w)&\\
+\bi(R_W,R_W)&.
\end{aligned}
\end{align*}
\end{document}


Noticed the changed placement of the alignment charecter in relation to the equals signs and the consequent use of extra braces as ={}& to ensure correct spacing. I have also defined your missing commands with \DeclareMathOperator. I chose to load mathtools instead of amsmath, but that is just personal preference; it loads amsmath anyway.

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Personally, I would write &= as I write always. And then use \! before the \begin{aligned}.... Shorter in my opinion (may be not truly aligned, but it looks well). –  Manuel Dec 3 '12 at 18:20
@Manuel That is what I usually do too, but in this case the misalignment seemed too much. I'll really have to understand one day what is going there. –  Andrew Swann Dec 3 '12 at 18:40
I have just ignored the usage of [t] in my trying. By the way, I think {}& just give the right (balance) spacing of =, is it right? –  user19832 Dec 17 '12 at 8:06
@user19832 The [t] or [b] option is very useful for fixing the vertical alignment. The documentation for the mathtools package uses ={}& almost everywhere in alignments. To my eyes (which often deceive me) it gives very tiny extra space in comparison with &=, but I haven't made any concrete measurements. –  Andrew Swann Dec 17 '12 at 9:48

Here's a couple of options- you didn't tell us what the \Ric command is- please always post a complete MWE :)

I would also use

\newcommand{\bi}{\operatorname{bi}}


for your \bi command, assuming I have interpreted it correctly.

\documentclass{article}
\usepackage{amsmath}
\newcommand{\Rico}{Ric_o}
%\newcommand{\bi}{\mathrm{bi}\,}
\newcommand{\bi}{\operatorname{bi}}

\begin{document}

\begin{align*}
Q(R)&=\bi(R,R)\\
&=\bi(R_I+R_{\Rico}+R_W,R_I+R_{\Rico}+R_W)\\
&=\bi(R_I,R_I)+2\bi(R_I,R_{\Rico})+2\bi(R_I,R_W)\\
&\phantom{{}=}+\bi(R_{\Rico},R_{\Rico})+2\bi(R_{\Rico},R_w)\\
&\phantom{{}=}+\bi(R_W,R_W).
\end{align*}

\begin{align*}
Q(R)&=\bi(R,R)\\
&=\bi(R_I+R_{\Rico}+R_W,R_I+R_{\Rico}+R_W)\\
&=\bi(R_I,R_I)+2\bi(R_I,R_{\Rico})+2\bi(R_I,R_W)\\
&&&+\bi(R_{\Rico},R_{\Rico})+2\bi(R_{\Rico},R_w)\\
&&&+\bi(R_W,R_W).
\end{align*}

\end{document}

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