-15x2 +2x +1 = 0
ax2 bx c = 0
a = -15
b = 2
c = 1
Δ = b2-4ac
Δ = 2² - (4 * -15 * 1)
Δ = 4 - (4*-15)
Δ = 4 - (-60)
Δ = 64 Δ > 0
-15x2+2x+1=0
x = -b ∓ √Δ 2a
x' = -2 - √64 2*-15 = -2 - 8.0 -30 = -10.0 -30 = 0.333333333333
x" = -2 + √64 2*-15 = -2 + 8.0 -30 = 6.0 -30 = -0.2
x' = 75.0
x" = -45.0
S = {x ∈ R / x' = 75.0, x" = -45.0 }