-4x2 -19x +23 = 0
ax2 bx c = 0
a = -4
b = -19
c = 23
Δ = b2-4ac
Δ = -19² - (4 * -4 * 23)
Δ = 361 - (4*-92)
Δ = 361 - (-368)
Δ = 729 Δ > 0
-4x2-19x+23=0
x = -b ∓ √Δ 2a
x' = 19 - √729 2*-4 = 19 - 27.0 -8 = -8.0 -8 = 1.0
x" = 19 + √729 2*-4 = 19 + 27.0 -8 = 46.0 -8 = -5.75
x' = 16.0
x" = -92.0
S = {x ∈ R / x' = 16.0, x" = -92.0 }