-4x2 +15x -14 = 0

ax2 bx c = 0

a = -4

b = 15

c = -14

Δ = b2-4ac

Δ = 15² - (4 * -4 * -14)

Δ = 225 - (4*56)

Δ = 225 - (224)

Δ = 1      Δ > 0

-4x2+15x-14=0

x = -b ∓ √Δ 2a

x' = -15 - √1 2*-4 = -15 - 1.0 -8 = -16.0 -8 = 2.0

x" = -15 + √1 2*-4 = -15 + 1.0 -8 = -14.0 -8 = 1.75

x' = 32.0

x" = 28.0

S = {x ∈ R / x' = 32.0, x" = 28.0 }