5x2 +22x +21 = 0
ax2 bx c = 0
a = 5
b = 22
c = 21
Δ = b2-4ac
Δ = 22² - (4 * 5 * 21)
Δ = 484 - (4*105)
Δ = 484 - (420)
Δ = 64 Δ > 0
5x2+22x+21=0
x = -b ∓ √Δ 2a
x' = -22 - √64 2*5 = -22 - 8.0 10 = -30.0 10 = -3.0
x" = -22 + √64 2*5 = -22 + 8.0 10 = -14.0 10 = -1.4
x' = -75.0
x" = -35.0
S = {x ∈ R / x' = -75.0, x" = -35.0 }