-9x2 -8x +17 = 0
ax2 bx c = 0
a = -9
b = -8
c = 17
Δ = b2-4ac
Δ = -8² - (4 * -9 * 17)
Δ = 64 - (4*-153)
Δ = 64 - (-612)
Δ = 676 Δ > 0
-9x2-8x+17=0
x = -b ∓ √Δ 2a
x' = 8 - √676 2*-9 = 8 - 26.0 -18 = -18.0 -18 = 1.0
x" = 8 + √676 2*-9 = 8 + 26.0 -18 = 34.0 -18 = -1.88888888889
x' = 81.0
x" = -153.0
S = {x ∈ R / x' = 81.0, x" = -153.0 }