Use the quadratic formula
\[
x=\frac{-b \pm \sqrt{b^2-4 a c}}{2 a}
\]
Once in standard form, identify \(\mathrm{a}, \mathrm{b}\) and \(\mathrm{c}\) from the original equation and plug them into the quadratic formula.
\[
\begin{aligned}
&x^2+2 x+1=0 \\
&a=1 \\
&b=2 \\
&c=1 \\
&x=\frac{-2 \pm \sqrt{2^2-4 \cdot 1 \cdot 1}}{2 \cdot 1}
\end{aligned}
\]
Evaluate the exponent
\[
\begin{aligned}
&x=\frac{-2 \pm \sqrt{2^2-4 \cdot 1 \cdot 1}}{2 \cdot 1} \\
&x=\frac{-2 \pm \sqrt{4-4 \cdot 1 \cdot 1}}{2 \cdot 1}
\end{aligned}
\]
Multiply the numbers
\[
\begin{aligned}
&x=\frac{-2 \pm \sqrt{4-4 \cdot 1 \cdot 1}}{2 \cdot 1} \\
&x=\frac{-2 \pm \sqrt{4-4}}{2 \cdot 1}
\end{aligned}
\]
Subtract the numbers
\[
\begin{aligned}
&x=\frac{-2 \pm \sqrt{4-4}}{2 \cdot 1} \\
&x=\frac{-2 \pm \sqrt{0}}{2 \cdot 1}
\end{aligned}
\]
Evaluate the square root
\[
\begin{aligned}
&x=\frac{-2 \pm \sqrt{0}}{2 \cdot 1} \\
&x=\frac{-2 \pm 0}{2 \cdot 1}
\end{aligned}
\]
Add zero
\[
\begin{aligned}
&x=\frac{-2 \pm 0}{2 \cdot 1} \\
&x=\frac{-2}{2 \cdot 1}
\end{aligned}
\]
Multiply the numbers
\[
\begin{aligned}
&x=\frac{-2}{2 \cdot 1} \\
&x=\frac{-2}{2}
\end{aligned}
\]
Cancel terms that are in both the numerator and denominator
\[
\begin{aligned}
&x=\frac{-2}{2} \\
&x=-1
\end{aligned}
\]