-15x2 +16x +15 = 0
ax2 bx c = 0
a = -15
b = 16
c = 15
Δ = b2-4ac
Δ = 16² - (4 * -15 * 15)
Δ = 256 - (4*-225)
Δ = 256 - (-900)
Δ = 1156 Δ > 0
-15x2+16x+15=0
x = -b ∓ √Δ 2a
x' = -16 - √1156 2*-15 = -16 - 34.0 -30 = -50.0 -30 = 1.66666666667
x" = -16 + √1156 2*-15 = -16 + 34.0 -30 = 18.0 -30 = -0.6
x' = 375.0
x" = -135.0
S = {x ∈ R / x' = 375.0, x" = -135.0 }