ExamBro
ExamBro
CUET · MATHS · PYQ PAPER 2025

If the matrix \(\left[\begin{array}{ccc}1 & 3 & 9 \\ 1 & x & x^2 \\ 4 & 6 & 9\end{array}\right]\) is a singular matrix, where \(x \in N\) (the set of natural numbers), then \(x\) is equal to

  1. A 2
  2. B 4
  3. C 3
  4. D 5
Verified Solution

Answer & Solution

Correct Answer

(C) 3

Step-by-step Solution

Detailed explanation

\( \begin{vmatrix} 1 & 3 & 9 \\ 1 & x & x^2 \\ 4 & 6 & 9 \end{vmatrix} = 0 \) \( 1(9x - 6x^2) - 3(9 - 4x^2) + 9(6 - 4x) = 0 \) \( 9x - 6x^2 - 27 + 12x^2 + 54 - 36x = 0 \) \( 6x^2 - 27x + 27 = 0 \) \( 2x^2 - 9x + 9 = 0 \) \( (2x - 3)(x - 3) = 0 \) \( x = \frac{3}{2} \) or…
From CUET
Explore more questions on app