-9x2 +14x +8 = 0
ax2 bx c = 0
a = -9
b = 14
c = 8
Δ = b2-4ac
Δ = 14² - (4 * -9 * 8)
Δ = 196 - (4*-72)
Δ = 196 - (-288)
Δ = 484 Δ > 0
-9x2+14x+8=0
x = -b ∓ √Δ 2a
x' = -14 - √484 2*-9 = -14 - 22.0 -18 = -36.0 -18 = 2.0
x" = -14 + √484 2*-9 = -14 + 22.0 -18 = 8.0 -18 = -0.444444444444
x' = 162.0
x" = -36.0
S = {x ∈ R / x' = 162.0, x" = -36.0 }