5x2 +22x -15 = 0
ax2 bx c = 0
a = 5
b = 22
c = -15
Δ = b2-4ac
Δ = 22² - (4 * 5 * -15)
Δ = 484 - (4*-75)
Δ = 484 - (-300)
Δ = 784 Δ > 0
5x2+22x-15=0
x = -b ∓ √Δ 2a
x' = -22 - √784 2*5 = -22 - 28.0 10 = -50.0 10 = -5.0
x" = -22 + √784 2*5 = -22 + 28.0 10 = 6.0 10 = 0.6
x' = -125.0
x" = 15.0
S = {x ∈ R / x' = -125.0, x" = 15.0 }