hey
i dont really have any notes i can give you but i can try and explain it to you...
In a Stretch: the points move at right angles to the invariant line
there are 2 basic transformation matrix for the stretch
1.) when the x-axis is the invariant line - [0 K] where k is the scale factor
[1 0]
2.) when the y-axis is the invariant line [0 1] where K is again the scale factor
[K 0]
In a Shear: the points move parallel to the invariant line
there are also 2 basic transformation matrix for the shear
1.) when the x-axis is the invariant line - [1 K]
[0 1]
2.) when the y-axis is the invariant line - [1 0]
[K 1]