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If the rank of the matrix `[[-1,2,5],[2,-4,a-4],[1,-2,a+1]]` is `1` then the value of `a` is (A) `-1` (B) 2 (C) `-6` (D) 4A. `2, if a=-6`B. `2, if a=1`C. `1, if a=2`D. `1, if a=-6` |
Answer» Correct Answer - B::D Let `A= [[-1, 2, 5],[2, -4, a-4],[1, -2, a+1]]` Applying `R_(2) rarr R_(2) 2 R_(1) and R_(3) rarr R_(3) + R_(1)`, then `A = [[-1, 2, 5],[0,0,a+6],[0,0,a+6]]` Applying `R_(3) rarr R_(3) - R_(2)`, then `A = [[-1, 2, 5],[0,0,a+6],[0,0,0]]` For `a = - 6 , p (A) = 1` For `a = 1,2,p (A) = 2` |
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