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 = -32.0 10 = -3.2
x" = -11 + √441 2*5 = -11 + 21.0 10 = 10.0 10 = 1.0
x' = -80.0
x" = 25.0
S = {x ∈ R / x' = -80.0, x" = 25.0 }