Show the Steps Taken to Solve an Equation

You should consider using amsmath:

\documentclass{article}
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\begin{align*}
  x^2 + 2x + 1 &= 0 \\
  (x+1)^2 &= 0 \\
  \llap{$\rightarrow$\hspace{50pt}} x &= -1
\end{align*}
\end{document}

Try this:

\begin{eqnarray}
 x^2+2x+1 &=& 0      \nonumber \\
 (x+1)^2  &=& 0 \nonumber \\
  x & = & -1
\end{eqnarray}

You might want to number each step by removing the \nonumber commands; I only numbered the last one.

More examples here.

There is a really neat package called witharrows that does a really nice job of what you're trying to do. It creates an environment called WithArrows that takes the place of aligned. There are several tweaks you can use to adjust the spacing, color, and types of arrows used to describe the steps.

Here is an MWE:

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}

\usepackage{witharrows}
    
%%%%%%%%%%%%%%%%%%%
    
    \begin{document}
        
    \begin{equation}
    \setlength{\jot}{10pt}
    \begin{WithArrows}
    ax^2 + bx + c & = 0 \Arrow[xoffset=-2cm]{Multiply both sides by $4a$} \\
    4a^2 x^2 + 4abx + 4ac & = 0 \Arrow[xoffset=-1cm]{Subtract $4ac$} \\
    4a^2 x^2 + 4abx & = - 4ac \\
    4a^2 x^2 + 4abx + b^2 & = b^2 - 4ac \\
    (2ax + b)^2 & = b^2 - 4ac \\
    2ax + b & = \pm \sqrt{b^2 - 4ac} \\
    2ax & = -b \pm \sqrt{b^2 - 4ac}
    \end{WithArrows}
    \nonumber
    \end{equation}

\end{document}

Here is the output: