N= [i,1;-1,i] I used this theorem: N N^{-1} = I_{n} Thus: [i,1;-1,i]*[a,b:c,d]=[1,1;1,1] I then found: ia+c=1 ib+d=1 -a+ic=1 -b+id=1 Can I conclude an inverse does not exist. If so, how? If not, what do I do? Thanks, Frank
I_{2} = [1, 0; 0, 1] What theorems have you learned about invertible matrices? (e.g. have you learned anything about how to tell if a matrix is invertible based on its determinant) Or, you could apply the algorithm for computing inverses and see if you get an answer or if its impossible.
I just found this: N^{-1} exists only if: det(NN^{-1} != 0 I'm a little rusty on my linear algebra, plus I got a concusion yesterday.
frankR, Hurkyl has told you what I_{2} is, because you got that wrong. Just redo your calculation using Hurkyl's hint and you should be able to answer this easily.