5x2 -11x -16 = 0
ax2 bx c = 0
a = 5
b = -11
c = -16
Δ = b2-4ac
Δ = -11² - (4 * 5 * -16)
Δ = 121 - (4*-80)
Δ = 121 - (-320)
Δ = 441 Δ > 0
5x2-11x-16=0
x = -b ∓ √Δ 2a
x' = 11 - √441 2*5 = 11 - 21.0 10 = -10.0 10 = -1.0
x" = 11 + √441 2*5 = 11 + 21.0 10 = 32.0 10 = 3.2
x' = -25.0
x" = 80.0
S = {x ∈ R / x' = -25.0, x" = 80.0 }