PLS HELP ME WITH # QUESTIONS, WILL GIVE BRAINLIEST! pls i really need your help

Determine if the equation defines y as a function of x: 2xy = 1. yes o no

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.

The value, v, of kalani’s stock investments over a time period, x, can be determined using the equation v=750(0.80)^-x. what is the rate of increase or decrease associated with this account? 20% decrease 20% increase 25% decrease 25% increase