[線代] symmetric, nonsingular

[mqazz1 (無法顯示)]

let A and B be n*n symmetric matrices and let C=AB. Is C symmetric?

let E and F be n*n elementary matrices and let C=EF. Is C nonsingular?


這兩題我直覺都是true

因為我看過這樣的題目

可是應該怎麼解釋呢?

謝謝

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