Re: [線代] rank
"=>"
Suppose not,
then
| a11 a12| |a11 a13| | a12 a13|
| a21 a22|,|a21 a23|, | a22 a23| is allzero
→rank(A)=0 or 1 →←
∴at least one of | a11 a12| |a11 a13| | a12 a13| is nonzero
| a21 a22|,|a21 a23|, | a22 a23|
"<="
∵ at least one of | a11 a12| |a11 a13| | a12 a13| is nonzero
| a21 a22|,|a21 a23|, | a22 a23|
∴rank(A)≧2
又∵矩陣A是2*3
∴rank(A)≦2
∴rank(A)=2
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04/08 00:10, , 1F
04/08 00:10, 1F
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