15x2 +19x -8 = 0
ax2 bx c = 0
a = 15
b = 19
c = -8
Δ = b2-4ac
Δ = 19² - (4 * 15 * -8)
Δ = 361 - (4*-120)
Δ = 361 - (-480)
Δ = 841 Δ > 0
15x2+19x-8=0
x = -b ∓ √Δ 2a
x' = -19 - √841 2*15 = -19 - 29.0 30 = -48.0 30 = -1.6
x" = -19 + √841 2*15 = -19 + 29.0 30 = 10.0 30 = 0.333333333333
x' = -360.0
x" = 75.0
S = {x ∈ R / x' = -360.0, x" = 75.0 }