[線代] 兩題矩陣性質的證明題

[Nohporelleb ()]

1. Show that all permustation matrices are normal.

2. Show that if A and B are both positive definite, so is A+B.



麻煩了，感謝指導！

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推 smartlwj    :2.for all x非0, x^t(A+B)x=x^tAx+x^tBx > 0