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Unformatted text preview: Solutions to problems from section 2.3 4. Is the matrix − 7 0 4 3 0 − 1 2 0 9 invertible? Solution: NO. The columns of the matrix above are linearly dependent, for = 0 − 7 3 2 + + 0 4 − 1 9 . Thus by the inverse matrix theorem (parts (e) and (a)) we know the matrix is singular. 6. Is the matrix 1 − 5 − 4 3 4 − 3 6 invertible? Solution: NO. Notice 1 − 5 − 4 3 4 − 3 6 NR 3 = R 3 +3 R 1 −→ 1 − 5 − 4 3 4 − 9 − 12 NR 3 = R 3 +3 R 2 −→ 1 − 5 − 4 3 4 Since the matrix has only 2 pivot positions we know the matrix is singular (by the IMT parts (c) and (a)). 8. Is the matrix 1 3 7 4 0 5 9 6 0 0 2 8 0 0 0 10 invertible? Solution: YES. There are 4 pivot positions, so by the IMT (parts (c) and (a)) we know the matrix above is invertible....
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This note was uploaded on 01/28/2010 for the course MATH 307 taught by Professor Axenovich during the Fall '08 term at Iowa State.
 Fall '08
 AXENOVICH

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