# how to change position of \Rightarrow

In the following example, how can I shift the \Rightarrow slightly towards left so that the first terms of both equations are vertically aligned?

\documentclass[10pt]{article}

\usepackage{mathtools}

\usepackage{mathtools}
\usepackage{amsmath}
\usepackage{amsthm} %for proof

\begin{document}

\begin{align*}
\frac{\partial V(u)}{\partial b}&=2.b.\sigma_{X}^{2}-2.\sigma_{XY}=0 \\
\Rightarrow b &=\frac{\sigma_{XY}}{\sigma_{X}^{2}} = \beta^{*}
\end{align*}

\end{document}


Since you are loading mathtools, you can use its \mathmakebox macro.

\documentclass[10pt]{article}

\usepackage{mathtools}

\usepackage{mathtools}
\mathmakebox[\widthof{$e\frac{\partial V(u)}{\partial b}$}][l]{\Rightarrow \hfill b} &=\frac{\sigma_{XY}}{\sigma_{X}^{2}} = \beta^{*}