# How to adjust the following split equation to be left aligned

I want to have the split equation on LHS to be left aligned. My 2 attempts are shown below, i.e., option A and option B. Please see the source code for the details.

\documentclass[10pt]{article}
\usepackage[a6paper,vmargin=15mm,hmargin=5mm]{geometry}
\usepackage{mathtools}

\begin{document}
\begin{enumerate}
\item Hey baby!
\item
\! \begin{aligned}[t] 2-3x(x-1)\\ {}-3(x-2y)(x+2y) &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3(x^2 +2xy -2xy -4y^2) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3(x^2 -4y^2) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3x^2 +12y^2 \end{multlined}\\ &= -6x^2 +3x +12y^2 +2 \end{aligned}
\item
\! \begin{aligned}[t] \begin{multlined}[t][4cm] 2-3x(x-1)\\ {}-3(x-2y)(x+2y) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3(x^2 +2xy -2xy -4y^2) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3(x^2 -4y^2) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3x^2 +12y^2 \end{multlined}\\ &= -6x^2 +3x +12y^2 +2 \end{aligned}
\end{enumerate}
\end{document}

How to solve this problem?

this will give you option b:

\documentclass[10pt]{article}
\usepackage[a6paper,vmargin=15mm,hmargin=5mm]{geometry}
\usepackage{mathtools}

\begin{document}
\begin{enumerate}
\setcounter{enumi}{2}
\item
\begin{multlined}[t] 2-3x(x-1)\\ \begin{aligned} {}-3(x-2y)(x+2y) &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3(x^2 +2xy -2xy -4y^2) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3(x^2 -4y^2) \end{multlined}\\ &= \! \begin{multlined}[t][4cm] 2 -3x^2 +3x\\ {}-3x^2 +12y^2 \end{multlined}\\ &= -6x^2 +3x +12y^2 +2 \end{aligned} \end{multlined}
\end{enumerate}

\end{document}

• Is \! needed for the outer multlined? – kiss my armpit Apr 16 '13 at 16:38
• @Bugbusters -- \! actually shouldn't be needed anywhere (in my example code); placing the & before the = establishes the correct spacing for the sign of relation. you don't want to start the expression with \! to avoid placing it too close to the item number, making that look like it's part of the equation. – barbara beeton Apr 16 '13 at 16:50