-6x2 +19x +7 = 0
ax2 bx c = 0
a = -6
b = 19
c = 7
Δ = b2-4ac
Δ = 19² - (4 * -6 * 7)
Δ = 361 - (4*-42)
Δ = 361 - (-168)
Δ = 529 Δ > 0
-6x2+19x+7=0
x = -b ∓ √Δ 2a
x' = -19 - √529 2*-6 = -19 - 23.0 -12 = -42.0 -12 = 3.5
x" = -19 + √529 2*-6 = -19 + 23.0 -12 = 4.0 -12 = -0.333333333333
x' = 126.0
x" = -12.0
S = {x ∈ R / x' = 126.0, x" = -12.0 }