\documentclass[10pt,a4paper]{article}
\usepackage{amsmath,nccmath}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\begin{document}
\begin{center}
\Large{\textbf{Equations in \LaTeX}}
\end{center}
\section*{Equation 1}
\begin{fleqn}
\[
x = \frac{-b \pm \sqrt{b^{2}-4ac}}{2a}
\]
\[
= \frac{-2 \pm \sqrt{2^{2}-4*(1)*(-8)}}{2*1}
\]
\[
= \frac{-2 \pm \sqrt{4+32}}{2}
\]
\end{fleqn}
\section*{Equation 2}
\begin{fleqn}
\[
\varphi^{\lambda}_{\sigma}A_{t} = \sum_{\pi \in C_{t}}
sgn(\pi)\varphi^{\lambda}_{\sigma}\varphi^{\lambda}_{\pi}
\]
\[
= \sum_{\tau \in C_{\sigma t}} sgn(\sigma^{-1}\tau\sigma)\varphi^{\lambda}_{\sigma}\varphi^{\lambda}_{\sigma^{-1}\tau\sigma}
\]
\[
= A_{\sigma t} \varphi^{\lambda}_{\sigma}
\]
\end{fleqn}
\end{document}