Please read the forum rules, it will increase your chance of getting help from the forum members.1) Do not create identical threads. Do not double post.
I have a start on this problem anyway . . .
Show that the lines: .
. . intersect or are parallel if and only if: .
The lines intersect if: .
. . That is, if the system: . . has a solution
Now we must relate this system to that determinant . . .
[But I truly dislike "if and only if" problems . . . p'too!]