-1x2 -17x +18 = 0
ax2 bx c = 0
a = -1
b = -17
c = 18
Δ = b2-4ac
Δ = -17² - (4 * -1 * 18)
Δ = 289 - (4*-18)
Δ = 289 - (-72)
Δ = 361 Δ > 0
-x2-17x+18=0
x = -b ∓ √Δ 2a
x' = 17 - √361 2*-1 = 17 - 19.0 -2 = -2.0 -2 = 1.0
x" = 17 + √361 2*-1 = 17 + 19.0 -2 = 36.0 -2 = -18.0
x' = 1.0
x" = -18.0
S = {x ∈ R / x' = 1.0, x" = -18.0 }