-15x2 +23x -8 = 0
ax2 bx c = 0
a = -15
b = 23
c = -8
Δ = b2-4ac
Δ = 23² - (4 * -15 * -8)
Δ = 529 - (4*120)
Δ = 529 - (480)
Δ = 49 Δ > 0
-15x2+23x-8=0
x = -b ∓ √Δ 2a
x' = -23 - √49 2*-15 = -23 - 7.0 -30 = -30.0 -30 = 1.0
x" = -23 + √49 2*-15 = -23 + 7.0 -30 = -16.0 -30 = 0.533333333333
x' = 225.0
x" = 120.0
S = {x ∈ R / x' = 225.0, x" = 120.0 }