5x2 -9x -14 = 0
ax2 bx c = 0
a = 5
b = -9
c = -14
Δ = b2-4ac
Δ = -9² - (4 * 5 * -14)
Δ = 81 - (4*-70)
Δ = 81 - (-280)
Δ = 361 Δ > 0
5x2-9x-14=0
x = -b ∓ √Δ 2a
x' = 9 - √361 2*5 = 9 - 19.0 10 = -10.0 10 = -1.0
x" = 9 + √361 2*5 = 9 + 19.0 10 = 28.0 10 = 2.8
x' = -25.0
x" = 70.0
S = {x ∈ R / x' = -25.0, x" = 70.0 }