Mathematics, Optimization, Data Science, Machine Learning, Duality.
value of the primal is equal to the dual at those 2 points, they are the optimal solutions to their respective problems. Namely, the optimal solution for the primal form is x₁ = 2/7 and x₂ = 3/7, while the optimal solution for the dual form is y₁ = 1/7 and y₂ = 3/7. Double check with graphical