If $f(x)=ax+b$ is linear, why is $f(\gamma x) \neq \gamma f(x)$
Note that
$$f(x)=ax+b$$
is said to be "linear" because its graph is a straight line but (for $b\neq 0$) it is not linear in the sense of "linear map" (e.g. $f(x)=ax$).
Note that
$$f(x)=ax+b$$
is said to be "linear" because its graph is a straight line but (for $b\neq 0$) it is not linear in the sense of "linear map" (e.g. $f(x)=ax$).