$\color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { - 9 \pm \sqrt{ 9 ^ { 2 } - 4 \times 1 \times 20 } } { 2 \times 1 } }$
$ $ Organize the expression $ $
$\color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { - 9 \pm \sqrt{ 1 } } { 2 \times 1 } }$
$x = \dfrac { - 9 \pm \sqrt{ \color{#FF6800}{ 1 } } } { 2 \times 1 }$
$n $ square root of 1 is 1 $ $
$x = \dfrac { - 9 \pm \color{#FF6800}{ 1 } } { 2 \times 1 }$
$x = \dfrac { - 9 \pm 1 } { 2 \color{#FF6800}{ \times } \color{#FF6800}{ 1 } }$
$ $ Multiplying any number by 1 does not change the value $ $
$x = \dfrac { - 9 \pm 1 } { \color{#FF6800}{ 2 } }$
$\color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { - 9 \pm 1 } { 2 } }$
$ $ Separate the answer $ $
$\begin{array} {l} \color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { - 9 + 1 } { 2 } } \\ \color{#FF6800}{ x } = \color{#FF6800}{ \dfrac { - 9 - 1 } { 2 } } \end{array}$
$\begin{array} {l} x = \dfrac { \color{#FF6800}{ - } \color{#FF6800}{ 9 } \color{#FF6800}{ + } \color{#FF6800}{ 1 } } { 2 } \\ x = \dfrac { - 9 - 1 } { 2 } \end{array}$
$ $ Add $ - 9 $ and $ 1$
$\begin{array} {l} x = \dfrac { \color{#FF6800}{ - } \color{#FF6800}{ 8 } } { 2 } \\ x = \dfrac { - 9 - 1 } { 2 } \end{array}$
$\begin{array} {l} x = \color{#FF6800}{ \dfrac { - 8 } { 2 } } \\ x = \dfrac { - 9 - 1 } { 2 } \end{array}$
$ $ Do the reduction of the fraction format $ $
$\begin{array} {l} x = \color{#FF6800}{ \dfrac { - 4 } { 1 } } \\ x = \dfrac { - 9 - 1 } { 2 } \end{array}$
$\begin{array} {l} x = \dfrac { - 4 } { \color{#FF6800}{ 1 } } \\ x = \dfrac { - 9 - 1 } { 2 } \end{array}$
$ $ If the denominator is 1, the denominator can be removed $ $
$\begin{array} {l} x = \color{#FF6800}{ - } \color{#FF6800}{ 4 } \\ x = \dfrac { - 9 - 1 } { 2 } \end{array}$
$\begin{array} {l} x = - 4 \\ x = \dfrac { \color{#FF6800}{ - } \color{#FF6800}{ 9 } \color{#FF6800}{ - } \color{#FF6800}{ 1 } } { 2 } \end{array}$
$ $ Find the sum of the negative numbers $ $
$\begin{array} {l} x = - 4 \\ x = \dfrac { \color{#FF6800}{ - } \color{#FF6800}{ 10 } } { 2 } \end{array}$
$\begin{array} {l} x = - 4 \\ x = \color{#FF6800}{ \dfrac { - 10 } { 2 } } \end{array}$
$ $ Do the reduction of the fraction format $ $
$\begin{array} {l} x = - 4 \\ x = \color{#FF6800}{ \dfrac { - 5 } { 1 } } \end{array}$
$\begin{array} {l} x = - 4 \\ x = \dfrac { - 5 } { \color{#FF6800}{ 1 } } \end{array}$
$ $ If the denominator is 1, the denominator can be removed $ $
$\begin{array} {l} x = - 4 \\ x = \color{#FF6800}{ - } \color{#FF6800}{ 5 } \end{array}$