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# FP4 invariant lines watch

2. (Original post by morgan8002)
I'm working from the AQA online textbook, page 99.

Find all invariant lines of the form y = mx, for the matrix transformations:
a.

I'm not too sure on how to do this and I'm not finding the textbook much help, so this is what I've done:

Bottom = m times the top

(always invariant),
,

However, the answer in the book is ,

Can someone tell me if the book's answer is correct? If it is, can you tell me where I went wrong. I've done this 10 times and haven't gotten their answer.

this is probably a lot quicker by eigenvectors (so you can check it ...)
3. (Original post by TeeEm)
this is probably a lot quicker by eigenvectors (so you can check it ...)
Sorry, was tired and I read the question wrong 10 times. It should be 15 not 18 in the top right of my matrix and it comes out. I though it was me not understanding the question.
4. (Original post by morgan8002)
Sorry, was tired and I read the question wrong 10 times. It should be 15 not 18 in the top right of my matrix and it comes out. I though it was me not understanding the question.
no worries
5. (Original post by TeeEm)
no worries
Thanks anyway.

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