-6x2 -x +7 = 0

ax2 bx c = 0

a = -6

b = -1

c = 7

Δ = b2-4ac

Δ = -² - (4 * -6 * 7)

Δ = 1 - (4*-42)

Δ = 1 - (-168)

Δ = 169      Δ > 0

-6x2-x+7=0

x = -b ∓ √Δ 2a

x' = 1 - √169 2*-6 = 1 - 13.0 -12 = -12.0 -12 = 1.0

x" = 1 + √169 2*-6 = 1 + 13.0 -12 = 14.0 -12 = -1.16666666667

x' = 36.0

x" = -42.0

S = {x ∈ R / x' = 36.0, x" = -42.0 }