Find value of k.

Question

k=?

(kA)^t (kA)=1, where A=[-2 1 -1].

The value of A is same but in column form.
[-2
1
-1]

Answer 1

I think that you mean that A^t = [-2    1   -1].  

 

Then (kA)^t(kA) = k²(A^tA) = k²{(-2)(-2) + (1)(1) + (-1)(-1)} = 6k²

 

So, if 6k² = 1, then k = √6/6.