29 Real numbers $x, y$ satisfy the equation $x^{2}+y^{2}-2 x+2 y-1=0$, then the maximum value of $k=\frac{y-3}{x}$ is
A. $2-\sqrt{17}$
B. $2+\sqrt{17}$
C. 8
D. does not exist
29 D. $k=\frac{y-3}{x-0}$ can be regarded as the slope of the line connecting the fixed point $A(0,3)$ and the point $M(x, y)$ on the circle $(x-1)^{2}+(y+1)^{2}=3$. Since the y-axis intersects the circle, as point $M$ approaches the y-axis along the circle, $k \rightarrow \infty$, so $k=\frac{y-3}{x-0}$ has no maximum value.