|x|-5 what does the vertical bar means?

Simply 8x squared + 5(7x squared- x) - 2x =

When you answer this can you explain

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.