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CUET · MATHS · PYQ PAPER 2025

For some constant 'k', if the system of linear equations
\(2 x-y+3 z=1\)
\(x-2 y+z=3\)
\(k x+y-z=0\)
has a unique solution, then

  1. A \(k=-\frac{4}{5}\)
  2. B \(k \neq-2\)
  3. C \(k \neq 2\)
  4. D \(k \neq-\frac{4}{5}\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(k \neq-\frac{4}{5}\)

Step-by-step Solution

Detailed explanation

\( \det \begin{pmatrix} 2 & -1 & 3 \\ 1 & -2 & 1 \\ k & 1 & -1 \end{pmatrix} \neq 0 \) \( 2((-2)(-1) - (1)(1)) - (-1)((1)(-1) - (1)(k)) + 3((1)(1) - (-2)(k)) \neq 0 \) \( 2(2 - 1) + (-1 - k) + 3(1 + 2k) \neq 0 \) \( 2 - 1 - k + 3 + 6k \neq 0 \) \( 4 + 5k \neq 0 \)…
From CUET
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