-1x2 -7x -12 = 0
ax2 bx c = 0
a = -1
b = -7
c = -12
Δ = b2-4ac
Δ = -7² - (4 * -1 * -12)
Δ = 49 - (4*12)
Δ = 49 - (48)
Δ = 1 Δ > 0
-x2-7x-12=0
x = -b ∓ √Δ 2a
x' = 7 - √1 2*-1 = 7 - 1.0 -2 = 6.0 -2 = -3.0
x" = 7 + √1 2*-1 = 7 + 1.0 -2 = 8.0 -2 = -4.0
x' = -3.0
x" = -4.0
S = {x ∈ R / x' = -3.0, x" = -4.0 }