If the normals at the four points (x₁,y₁) (x₂,y₂) (x₃,y₃) (x4₄,y4₄) on the ellipse x²/a² + y²/b² = 1 are concurrent find te value of (⁴∑ᵢ₌₁ Xᵢ)(⁴∑ᵢ₌₁ 1/Xᵢ)