Linear Algebra - Homogenous Coordinates

[gotpho]

Homework Statement
Find a 3x3 matrix produces the following 2D composites transformation by translation and reflection about the line x=-3

The attempt at a solution

I understand translation but how do you go about doing reflection? I'm guessing for reflection, I need to do a conjugation? So I need to move the line from the origin to x=-3.Do I simply multiply -3 to the standard matrix of the line about x?

I have asked in another site but no one seems to be answering. Any kind of help will be appreciated.

 

[gotpho]

I done a little thinking and is it possible that the transformation for the reflection is the identity multiply the line.

so

1 0 -3 -3
X =
0 1 0 0

thus the transformation matrix for the reflection is

1 0 -3
0 1 0
0 0 1


Can anyone help? I really need the help.