2010-02-23

線代 ,Show that no 2*2 matrices A and B exist that satisfy the matrix equation AB-BA=I

請問這裡這麼解阿?

Show that no 2*2 matrices A and B exist that satisfy the matrix equation AB-BA=I


用determine嗎? det(AB)=det(BA)
det(AB)-det(BA) =0
det(I)=1
矛盾

旦 det(AB-BA) 會等 det(AB)-det(BA) ?

2 則留言:

pai 提到...

用trace
tr(AB-BA)=tr(I)
tr(AB)-tr(BA)=2 所以-><-
因為tr(AB)=tr(BA)

若拙 提到...

挖哩勒 原來是用TR唷
哈哈 我想超久 我還去翻書
發現DET(AB-BA)不一定等於DET(AB)-DET(BA)
這樣就知道嚕~ 謝嚕大大~