5x2 +19x +18 = 0
ax2 bx c = 0
a = 5
b = 19
c = 18
Δ = b2-4ac
Δ = 19² - (4 * 5 * 18)
Δ = 361 - (4*90)
Δ = 361 - (360)
Δ = 1 Δ > 0
5x2+19x+18=0
x = -b ∓ √Δ 2a
x' = -19 - √1 2*5 = -19 - 1.0 10 = -20.0 10 = -2.0
x" = -19 + √1 2*5 = -19 + 1.0 10 = -18.0 10 = -1.8
x' = -50.0
x" = -45.0
S = {x ∈ R / x' = -50.0, x" = -45.0 }