Let's solve in ℝ: x2 + 2x + 5 = 0 Given the quadratic form ax2 + bx + c, you can calculate the discriminant: Δ = b2 -4ac Δ = 22 -4·1·5 Δ = 4 -4·5 Δ = 4 -20 Δ = -16 Since Δ < 0, the equation has no solution. No solution in ℝ for: x ▶Solution: x ∈ ∅