10.4#5 (Edited)

I still have a question about number 5. It asks:
Find two unit vectors orthogonal to a=⟨−4,1,4⟩ and b=<5, -4, 3>

Enter your answer so that the first non-zero coordinate of the first vector is positive.
I attached my work below so you can see my thought process; however, I keep getting the k coordinates incorrect and I'm not sure where I'm going wrong.
Thank you for you time,

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It looks to me like you've done it correctly.  BUT, if you click the "Email Instructor" button down at the bottom of the web page of your problem it will give me what you've done and what your numbers are so I can see exactly how and why it's misbehaving.

(Edit)
OK, you did that. Playing around with the webwork, it looks like all it wants is four decimal points instead of three.