5x2 +7x +2 = 0
ax2 bx c = 0
a = 5
b = 7
c = 2
Δ = b2-4ac
Δ = 7² - (4 * 5 * 2)
Δ = 49 - (4*10)
Δ = 49 - (40)
Δ = 9 Δ > 0
5x2+7x+2=0
x = -b ∓ √Δ 2a
x' = -7 - √9 2*5 = -7 - 3.0 10 = -10.0 10 = -1.0
x" = -7 + √9 2*5 = -7 + 3.0 10 = -4.0 10 = -0.4
x' = -25.0
x" = -10.0
S = {x ∈ R / x' = -25.0, x" = -10.0 }