Textbook Problem

Response to adrenalin Experimental evidence suggests that the response y of the body to the concentration x of injected adrenalin is given by

$y=\frac{x}{a+bx}$ where a and b are experimental constants.

(a) Is this function continuous for all x?

(b) On the basis of your conclusion in part (a) and the fact that in the context of the application $x\ge 0\text{ and }y\ge 0$, must a and b both be positive, both be negative, or have opposite signs?