-1x2 -9x +22 = 0
ax2 bx c = 0
a = -1
b = -9
c = 22
Δ = b2-4ac
Δ = -9² - (4 * -1 * 22)
Δ = 81 - (4*-22)
Δ = 81 - (-88)
Δ = 169 Δ > 0
-x2-9x+22=0
x = -b ∓ √Δ 2a
x' = 9 - √169 2*-1 = 9 - 13.0 -2 = -4.0 -2 = 2.0
x" = 9 + √169 2*-1 = 9 + 13.0 -2 = 22.0 -2 = -11.0
x' = 2.0
x" = -11.0
S = {x ∈ R / x' = 2.0, x" = -11.0 }