YES I know a Linear Mapping $f(x)$ is actually which satisfy $f(ax+y)$=$a \cdot f(x)$+$f(y)$.
But I just wondered $f(x)=m \cdot x+c$ is not a linear map even though it's graph is a straight line which is linear obviously why is this so?
kindly help, thanx n regards.
The words map and function generally mean the same thing.
The problem here is the abuse of terminology for linear function for something like $x\mapsto a+bx$. This is properly an affine function, at least to mathematicians when being precise in their diction.
Terminology shifts over the years, and once this usage of the term "linear" was correct. These shifts reach different parts of the world at different times, and this particular change has not reached the sciences in general, nor (I suspect) many school rooms.