$x^2+5x-36$ = 0

D = ${\left(\frac{5}{2}\right)}^2-\left(-36\right)$ = $\frac{25}{4}$$+$ $36$ = $\frac{25}{4}$$+$ $\frac{144}{4}$ = $\frac{169}{4}$

x_1,2 = $-\frac{5}{2}$ ± $\sqrt{\frac{169}{4}}$

x₁ = $-\frac{5}{2}$ - $\frac{13}{2}$ = $-\frac{18}{2}$ = -9

x₂ = $-\frac{5}{2}$ + $\frac{13}{2}$ = $\frac{8}{2}$ = 4

L = { $-9$; $4$}

$-18x+x^2+80$ = 0

sortieren

$x^2-18x+80$ = 0

D = ${\left(-9\right)}^2-80$ = $81$ $-$ $80$ = $1$

x_1,2 = $9$ ± $\sqrt{1}$

x₁ = $9$ - $1$ = 8

x₂ = $9$ + $1$ = 10

L = { $8$; $10$}