-6x2 -19x -13 = 0
ax2 bx c = 0
a = -6
b = -19
c = -13
Δ = b2-4ac
Δ = -19² - (4 * -6 * -13)
Δ = 361 - (4*78)
Δ = 361 - (312)
Δ = 49 Δ > 0
-6x2-19x-13=0
x = -b ∓ √Δ 2a
x' = 19 - √49 2*-6 = 19 - 7.0 -12 = 12.0 -12 = -1.0
x" = 19 + √49 2*-6 = 19 + 7.0 -12 = 26.0 -12 = -2.16666666667
x' = -36.0
x" = -78.0
S = {x ∈ R / x' = -36.0, x" = -78.0 }