-9x2 +14x -5 = 0
ax2 bx c = 0
a = -9
b = 14
c = -5
Δ = b2-4ac
Δ = 14² - (4 * -9 * -5)
Δ = 196 - (4*45)
Δ = 196 - (180)
Δ = 16 Δ > 0
-9x2+14x-5=0
x = -b ∓ √Δ 2a
x' = -14 - √16 2*-9 = -14 - 4.0 -18 = -18.0 -18 = 1.0
x" = -14 + √16 2*-9 = -14 + 4.0 -18 = -10.0 -18 = 0.555555555556
x' = 81.0
x" = 45.0
S = {x ∈ R / x' = 81.0, x" = 45.0 }