5x2 +2x -7 = 0
ax2 bx c = 0
a = 5
b = 2
c = -7
Δ = b2-4ac
Δ = 2² - (4 * 5 * -7)
Δ = 4 - (4*-35)
Δ = 4 - (-140)
Δ = 144 Δ > 0
5x2+2x-7=0
x = -b ∓ √Δ 2a
x' = -2 - √144 2*5 = -2 - 12.0 10 = -14.0 10 = -1.4
x" = -2 + √144 2*5 = -2 + 12.0 10 = 10.0 10 = 1.0
x' = -35.0
x" = 25.0
S = {x ∈ R / x' = -35.0, x" = 25.0 }