15x2 +13x -2 = 0
ax2 bx c = 0
a = 15
b = 13
c = -2
Δ = b2-4ac
Δ = 13² - (4 * 15 * -2)
Δ = 169 - (4*-30)
Δ = 169 - (-120)
Δ = 289 Δ > 0
15x2+13x-2=0
x = -b ∓ √Δ 2a
x' = -13 - √289 2*15 = -13 - 17.0 30 = -30.0 30 = -1.0
x" = -13 + √289 2*15 = -13 + 17.0 30 = 4.0 30 = 0.133333333333
x' = -225.0
x" = 30.0
S = {x ∈ R / x' = -225.0, x" = 30.0 }