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

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

Da die Diskriminante D < 0 ist, hat die quadratische Gleichung keine Lösunng.

L ={}

$-90+x+x^2$ = 0

sortieren

$x^2+x-90$ = 0

D = ${\left(\frac{1}{2}\right)}^2-\left(-90\right)$ = $\frac{1}{4}$$+$ $90$ = $\frac{1}{4}$$+$ $\frac{360}{4}$ = $\frac{361}{4}$

x_1,2 = $-\frac{1}{2}$ ± $\sqrt{\frac{361}{4}}$

x₁ = $-\frac{1}{2}$ - $\frac{19}{2}$ = $-\frac{20}{2}$ = -10

x₂ = $-\frac{1}{2}$ + $\frac{19}{2}$ = $\frac{18}{2}$ = 9

L = { $-10$; $9$}