Definition of Constant Function
- Constant function is a linear function of the form y = b, where b is a constant.
- It is also written as f(x) = b.
- The graph of a constant function is a horizontal line.
Now, if by the strictest rule of a linear function being functions that have x as the input variable, and x is raised only to the first power, one might interpret f(x)=b as non-linear, since it is a polynomial function of degree 0. To me, this is a stretch (departure) from the difinition of the term "linear" (the graph of which is a straight line).