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Question : 5 of 160
Marks:
+1,
-0
Solution:
Consider the matrix.
[| 3 | 5 | −1 | 4 |
| 2 | 1 | 3 | −2 |
| 8 | 11 | 1 | 6 |
| −7 | −14 | 6 | −14 |
] Apply operation
R1→R1−R2 [| 1 | 4 | −4 | 6 |
| 2 | 1 | 3 | −2 |
| 8 | 11 | 1 | 6 |
| −7 | −14 | 6 | −14 |
] Apply operation
R2→R2−2R1,R3→R3−8R1 and
R4→R4+7R1 [| 1 | 4 | −4 | 6 |
| 0 | −7 | 11 | −14 |
| 0 | −21 | 33 | −42 |
| 0 | 14 | −22 | 28 |
] Apply operation
R3→R3−3R2 [| 1 | 4 | −4 | 6 |
| 0 | −7 | 11 | −14 |
| 0 | 0 | 0 | 0 |
| 0 | 14 | −22 | 28 |
] Apply operation
R3↔R4 [| 1 | 4 | −4 | 6 |
| 0 | −7 | 11 | −14 |
| 0 | 14 | −22 | 28 |
| 0 | 0 | 0 | 0 |
] Apply operation
R3→R3+2R2 [| 1 | 4 | −4 | 6 |
| 0 | −7 | 11 | −14 |
| 0 | 0 | 0 | 0 |
| 0 | 0 | 0 | 0 |
] Therefore, the rank of the matrix is 2
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