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 = 18.0 10 = 1.8
x" = 19 + √1 2*5 = 19 + 1.0 10 = 20.0 10 = 2.0
x' = 45.0
x" = 50.0
S = {x ∈ R / x' = 45.0, x" = 50.0 }