Medium MCQ +4 / -1 PYQ · JEE Mains 2022

The system of equations

$- kx + 3y - 14z = 25$

$- 15x + 4y - kz = 3$

$- 4x + y + 3z = 4$

is consistent for all k in the set

  1. A R
  2. B R $-$ {$-$11, 13}
  3. C R $-$ {13}
  4. D R $-$ {$-$11, 11} Correct answer

Solution

<p>The system may be inconsistent if</p> <p>$$\left| {\matrix{ { - k} & 3 & { - 14} \cr { - 15} & 4 & { - k} \cr { - 4} & 1 & 3 \cr } } \right| = 0 \Rightarrow k = \, \pm \,11$$</p> <p>Hence if system is consistent then $k \in R - \{ 11, - 11\}$.</p>

About this question

Subject: Mathematics · Chapter: Matrices and Determinants · Topic: Types of Matrices and Operations

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