What is the equation of the piecewise function

Is the square root of 4 plus the square root of 16 rational?

Do some research and find a city that has experienced population growth. determine its population on january 1st of a certain year. write an exponential function to represent the city’s population, y, based on the number of years that pass, x after a period of exponential growth. describe the variables and numbers that you used in your equation.

I’m really confused and need to learn this