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 = -28.0 10 = -2.8
x" = -9 + √361 2*5 = -9 + 19.0 10 = 10.0 10 = 1.0
x' = -70.0
x" = 25.0
S = {x ∈ R / x' = -70.0, x" = 25.0 }