$x^2+8x+7$ = 0

D = $4^2-7$ = $16$ $-$ $7$ = $9$

x_1,2 = $-4$ ± $\sqrt{9}$

x₁ = $-4$ - $3$ = -7

x₂ = $-4$ + $3$ = -1

L = { $-7$; $-1$}

$-6x-7+x^2$ = 0

sortieren

$x^2-6x-7$ = 0

D = ${\left(-3\right)}^2-\left(-7\right)$ = $9$$+$ $7$ = $16$

x_1,2 = $3$ ± $\sqrt{16}$

x₁ = $3$ - $4$ = -1

x₂ = $3$ + $4$ = 7

L = { $-1$; $7$}