:{| style="text-align: left;"
|-
| &nbsp;
| rowspan="2" | &nbsp;
| rowspan="2" |<math>a \cdot x^2 + b \cdot x + c = 0</math>
| rowspan="2" | &nbsp;
| rowspan="2" |Den givne ligning
|-
| rowspan="2" | <math>\Updownarrow</math>
|-
| rowspan="2" | &nbsp;
| rowspan="2" |<math>4 \cdot a \cdot a \cdot x^2 + 4 \cdot a \cdot b \cdot x + 4 \cdot a \cdot c = 0</math>
| rowspan="2" | &nbsp;
| rowspan="2" |Multiplikation med <math>4 \cdot a</math>; lovligt, da <math>a \ne 0</math>
|-
| rowspan="2" | <math>\Updownarrow</math>
|-
| rowspan="2" | &nbsp;
| rowspan="2" |<math>({\color{Green} 2 \cdot a \cdot x} )^2 + 2 \cdot ({\color{Green} 2 \cdot a \cdot x}) \cdot {\color{Red} b} + {\color{Red} b}^2 - b^2 + 4 \cdot a \cdot c = 0</math>
| rowspan="2" | &nbsp;
| rowspan="2" |Faktorisering og addition af <math>b^2 - b^2</math>
|-
| rowspan="2" | <math>\Updownarrow</math>
|-
| rowspan="2" | &nbsp;
| rowspan="2" |<math>({\color{NavyBlue} 2 \cdot a \cdot x + b})^2  - b^2 + 4 \cdot a \cdot c = 0</math>
| rowspan="2" | &nbsp;
| rowspan="2" |Anvendelse af [[Kvadratsætninger|første kvadratsætning]].
|-
| rowspan="2" | <math>\Updownarrow</math>
|-
| rowspan="2" | &nbsp;
| rowspan="2" |<math>(2 \cdot a \cdot x + b)^2  = b^2 - 4 \cdot a \cdot c</math>
| rowspan="2" | &nbsp;
| rowspan="2" |Konstantled flyttes til højre side
|-
| rowspan="2" | <math>\Updownarrow</math>
|-
| rowspan="2" | &nbsp;
| rowspan="2" |<math>(2 \cdot a \cdot x + b)^2  = d</math>
| rowspan="2" | &nbsp;
| rowspan="2" |Kombinationen af koefficienterne betegnes <math>d</math>
|-
| &nbsp;
|}
Matematik