Wow. I couldn't perceive till I see from this lect. that the Lagrange multiplier method,  example, that the maximum values of  f are found at infinity to the hyperbola.####[['lect', 'Course_General_Feedback', 'POS'], ['Lagrange multiplier method', 'Mathematical_Related_Concept', 'NEU'], ['maximum values of f', 'Mathematical_Related_Concept', 'NEU'], ['infinity', 'Mathematical_Related_Concept', 'NEU'], ['hyperbola', 'Mathematical_Related_Concept', 'NEU']]