It is a constant of variation. All direct variations are linear functions, but not all linear functions are direct variations. Steepness is related to the constant of variation. Constant variation can't be 0. Constant of variation means that x and y constantly vary at the same rate.
All direct variations go through the origin.
A direct variation is when x is multiplied by a fixed number other than zero or the constant of variation to equal y. There are two variables that are said to vary directly, and the function relating them is called a direct variation. If you graph a direct variation, it goes through the origin. The steeper the line is, is related to the amount of the constant of variation. The greater the constant of variation, the steeper the line.