I became very confused about linear functions after reading this question What is the difference between linear and affine function
In the comments it says that $F(x)=2*x+4$ is NOT a linear function , (but an affine one). All my professors gave such examples when teaching linear functions. I am really confused now.
Should a linear function always be of the form $f(x)=t*x$ , where t is a constant ?
I think this could help me understand better linear transformations. I think one of the reasons I did not understand them is because I had a slightly wrong definition of linear functions.
HOWEVER, on Wikipedia, the definition of linear functions seems to accepts functions that also have a constant added or subtracted from the first (linear?) part.
So is wikipedia wrong on this one ?