題組內容
2. (50%) Answer the following questions.
(a) Given \( y = \frac{x1^2 + x2^2}{x1 + x2} \), find the total differential \( dy \).
2. (50%) Answer the following questions.
(a) Given \( y = \frac{x1^2 + x2^2}{x1 + x2} \), find the total differential \( dy \).