-1x2 +9x -8 = 0
ax2 bx c = 0
a = -1
b = 9
c = -8
Δ = b2-4ac
Δ = 9² - (4 * -1 * -8)
Δ = 81 - (4*8)
Δ = 81 - (32)
Δ = 49 Δ > 0
-x2+9x-8=0
x = -b ∓ √Δ 2a
x' = -9 - √49 2*-1 = -9 - 7.0 -2 = -16.0 -2 = 8.0
x" = -9 + √49 2*-1 = -9 + 7.0 -2 = -2.0 -2 = 1.0
x' = 8.0
x" = 1.0
S = {x ∈ R / x' = 8.0, x" = 1.0 }