A transformation in equation 1.2 is called infinitesimal if are small quantities so that their squares and products can be neglected.
As a result, the quantities: , and, which are the differences of the coordinates of the same point before and after transformation are also infinitesimal.
It can be shown that result of two infinitesimal affine transformations is also affine.
are small quantities so that their squares and products can be neglected. 
, 
and
, which are the differences of the coordinates of the same point before and after transformation are also infinitesimal. 
