题目
设 z = x^y + (y)/(x)，则 dz = ( ).A. yx^y-1dx + (x^y ln x + (1)/(x))dyB. (yx^y-1 - (y)/(x^2))dx + (x^y ln x + (1)/(x))dyC. (yx^y-1 - (y)/(x^2))dx + (x^y ln x)dyD. (yx^y-1 + (y)/(x^2))dx + (x^y ln x + (1)/(x))dy
设 $z = x^y + \frac{y}{x}$，则 $dz = (\quad)$.
A. $yx^{y-1}dx + \left(x^y \ln x + \frac{1}{x}\right)dy$
B. $\left(yx^{y-1} - \frac{y}{x^2}\right)dx + \left(x^y \ln x + \frac{1}{x}\right)dy$
C. $\left(yx^{y-1} - \frac{y}{x^2}\right)dx + \left(x^y \ln x\right)dy$
D. $\left(yx^{y-1} + \frac{y}{x^2}\right)dx + \left(x^y \ln x + \frac{1}{x}\right)dy$
题目解答
答案
B. $\left(yx^{y-1} - \frac{y}{x^2}\right)dx + \left(x^y \ln x + \frac{1}{x}\right)dy$