Rumus yang digunakan:
\begin{equation*}
\begin{split}
a^2 + 2ab + b^2 & = (a + b)^2 \\\\
a^2 - 2ab + b^2 & = (a - b)^2
\end{split}
\end{equation*}
Contoh 01
\begin{equation*}
\begin{split}
& x^2 + 6x + 9 = 0 \\\\
& x^2 + 2 \:.\: 3 \:.\: x + 3^2 = 0 \\\\
& (x + 3)^2 = 0 \\\\
& x + 3 = 0 \\\\
& x = -3
\end{split}
\end{equation*}
Contoh 02
\begin{equation*}
\begin{split}
& x^2 - 8x + 16 = 0 \\\\
& x^2 - 2 \:.\: 4 \:.\: x + 4^2 = 0 \\\\
& (x - 4)^2 = 0 \\\\
& x - 4 = 0 \\\\
& x = 4
\end{split}
\end{equation*}