-9x2 +13x +22 = 0
ax2 bx c = 0
a = -9
b = 13
c = 22
Δ = b2-4ac
Δ = 13² - (4 * -9 * 22)
Δ = 169 - (4*-198)
Δ = 169 - (-792)
Δ = 961 Δ > 0
-9x2+13x+22=0
x = -b ∓ √Δ 2a
x' = -13 - √961 2*-9 = -13 - 31.0 -18 = -44.0 -18 = 2.44444444444
x" = -13 + √961 2*-9 = -13 + 31.0 -18 = 18.0 -18 = -1.0
x' = 198.0
x" = -81.0
S = {x ∈ R / x' = 198.0, x" = -81.0 }