You get points so why not someone out

How do i do this? i don’t understand

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

Identify all the cases where non-probability sampling is used when attempting to study the characteristics of a large city. studies on every subject in the population divide a population in groups and obtain a sample studies with a limited amount of time demonstrate existing traits in a population studies with the nth person selected