$x^2-4$ = 0

D = $0^2-\left(-4\right)$ = $0$$+$ $4$ = $4$

x_1,2 = $0$ ± $\sqrt{4}$

x₁ = $0$ - $2$ = -2

x₂ = $0$ + $2$ = 2

L = { $-2$; $2$}

$x^2-4$ = $3x$ | - ( $3x$)

$x^2-4-3x$ = 0

sortieren

$x^2-3x-4$ = 0

D = ${\left(-\frac{3}{2}\right)}^2-\left(-4\right)$ = $\frac{9}{4}$$+$ $4$ = $\frac{9}{4}$$+$ $\frac{16}{4}$ = $\frac{25}{4}$

x_1,2 = $\frac{3}{2}$ ± $\sqrt{\frac{25}{4}}$

x₁ = $\frac{3}{2}$ - $\frac{5}{2}$ = $-\frac{2}{2}$ = -1

x₂ = $\frac{3}{2}$ + $\frac{5}{2}$ = $\frac{8}{2}$ = 4

L = { $-1$; $4$}