5x2 -19x +12 = 0
ax2 bx c = 0
a = 5
b = -19
c = 12
Δ = b2-4ac
Δ = -19² - (4 * 5 * 12)
Δ = 361 - (4*60)
Δ = 361 - (240)
Δ = 121 Δ > 0
5x2-19x+12=0
x = -b ∓ √Δ 2a
x' = 19 - √121 2*5 = 19 - 11.0 10 = 8.0 10 = 0.8
x" = 19 + √121 2*5 = 19 + 11.0 10 = 30.0 10 = 3.0
x' = 20.0
x" = 75.0
S = {x ∈ R / x' = 20.0, x" = 75.0 }