答案1
我猜你想要其中一种对齐方式?
\documentclass[11pt]{article}
\usepackage[margin=1in]{geometry}
\usepackage{mathtools, nccmath}
\begin{document}
\begin{alignat*}{2}
& & g(bL) &= F(b,g(L))\\
& \implies & g((1+\varepsilon)L) &= F((1+\epsilon),g(L))\\
& \implies & g((1+ \varepsilon)L)-g(L) &= F((1+\epsilon),g(L))-F(1,g(L))
\end{alignat*}
\vskip 1cm
\begin{fleqn}
\begin{alignat*}{2}
& & g(bL) &= F(b,g(L))\\
& \implies & g((1+\varepsilon)L) &= F((1+\epsilon),g(L))\\
& \implies & g((1+ \varepsilon)L)-g(L) &= F((1+\epsilon),g(L))-F(1,g(L))
\end{alignat*}
\end{fleqn}
\end{document}