16. How many times does the graph of $y= \pm \sqrt{\frac{x-1}{x+1}}$ cross the $x$-axis, the $y$-axis or the line $y=x ?$
(ans. Twice, at $(1,0)$ and in the third quadrant.
First $x \geq 1$ or $x1$ or $y<-1$ with $x=-1$ as asymptote. $y=x$ intersects this portion of the graph once in the third quadrant.)