It depends on your definition of linear. In some algebra contexts you would call it a linear function because it's a line, but in linear algebra you would not c

It depends on your definition of linear. In some algebra contexts you would call it a linear function because it's a line, but in linear algebra you would not consider it a linear transformation because it doesn't pass through the origin[1]. It would be more accurate to call it "affine." [1] More generally, being "linear" means that f(ax+y) = af(x) + f(y) for constant a and variables x, y. From this, it follows that f(0) = 0 for linear transformations.