-4x2 -2x +20 = 0
ax2 bx c = 0
a = -4
b = -2
c = 20
Δ = b2-4ac
Δ = -2² - (4 * -4 * 20)
Δ = 4 - (4*-80)
Δ = 4 - (-320)
Δ = 324 Δ > 0
-4x2-2x+20=0
x = -b ∓ √Δ 2a
x' = 2 - √324 2*-4 = 2 - 18.0 -8 = -16.0 -8 = 2.0
x" = 2 + √324 2*-4 = 2 + 18.0 -8 = 20.0 -8 = -2.5
x' = 32.0
x" = -40.0
S = {x ∈ R / x' = 32.0, x" = -40.0 }