A linear function is a specific type of function that represents the relationship between two variables, usually x and y. The graph of this function is a line. How do I know this? Well, see below for an explanation!
Whenever I learned about functions, the first thing I was told was that x cannot repeat. If x repeats, your result is not a function. For a number or ordered pair to be a function, the points should be able to pass the vertical line test. The vertical line test is an observation to see if two points are on the same vertical line. If they are, then your pair isn’t a function. If none of the pairs are on the same vertical line, you have a function. I also learned that when talking about linear functions, a shortcut to use is that linear has the word “line” in it. This means that a straight line needs to be made for a valid relationship to be present between two variables. The line cannot curve, it cannot touch any of the points it has (for example, a circle), and it must be straight all the way through. If you need any extra help to understand this, let me know and I will gladly assist you.