题目
6.(单选题，9分)设u=xy+(y)/(x),则(partial^2u)/(partial x^2)=（）A. y-(y)/(x^2)B. (2y)/(x^3)C. (y)/(x^2)-yD. -(2y)/(x^3)
6.(单选题，9分)
设$u=xy+\frac{y}{x}$,则$\frac{\partial^{2}u}{\partial x^{2}}$=（）
A. $y-\frac{y}{x^{2}}$
B. $\frac{2y}{x^{3}}$
C. $\frac{y}{x^{2}}-y$
D. $-\frac{2y}{x^{3}}$
题目解答
答案
B. $\frac{2y}{x^{3}}$