15x2 +11x -12 = 0
ax2 bx c = 0
a = 15
b = 11
c = -12
Δ = b2-4ac
Δ = 11² - (4 * 15 * -12)
Δ = 121 - (4*-180)
Δ = 121 - (-720)
Δ = 841 Δ > 0
15x2+11x-12=0
x = -b ∓ √Δ 2a
x' = -11 - √841 2*15 = -11 - 29.0 30 = -40.0 30 = -1.33333333333
x" = -11 + √841 2*15 = -11 + 29.0 30 = 18.0 30 = 0.6
x' = -300.0
x" = 135.0
S = {x ∈ R / x' = -300.0, x" = 135.0 }