Exercise 3.B.4

Show that

{ T L ( R 5 , R 4 ) : dim null  T > 2 }

is not a subspace of L ( R 5 , R 4 )

Answers

Let T 1 , T 2 L ( R 5 , R 4 ) and dim null T 1 and dim null T 2 > 2 where

T 1 ( x 1 , x 2 , x 3 , x 4 , x 5 ) = ( x 1 , 0 , 0 , 0 )

T 2 ( x 1 , x 2 , x 3 , x 4 , x 5 ) = ( 0 , x 2 , 0 , 0 )

However, dim null ( T 1 + T 2 ) = 2 , so it is not a subspace.

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2025-03-28 23:05
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