I'm guessing you mean what a linear function is, answer provided below...
What is a linear function?:
linear functions are those whose graph is a straight line. A linear function has the following form. y = f(x) = a + bx. A linear function has one independent variable and one dependent variable.
How to determine a linear function:
1. Identify the y-intercept from the graph.
2. Choose two points to determine the slope.
3. Substitute the y-intercept and slope into slope-intercept form of a line.
Here is a graph with a linear function:
