-9x2 +23x +12 = 0
ax2 bx c = 0
a = -9
b = 23
c = 12
Δ = b2-4ac
Δ = 23² - (4 * -9 * 12)
Δ = 529 - (4*-108)
Δ = 529 - (-432)
Δ = 961 Δ > 0
-9x2+23x+12=0
x = -b ∓ √Δ 2a
x' = -23 - √961 2*-9 = -23 - 31.0 -18 = -54.0 -18 = 3.0
x" = -23 + √961 2*-9 = -23 + 31.0 -18 = 8.0 -18 = -0.444444444444
x' = 243.0
x" = -36.0
S = {x ∈ R / x' = 243.0, x" = -36.0 }