Question

If \(\rm \begin{vmatrix} 3&\rm x \\ \rm x&1 \end{vmatrix}=\begin{vmatrix} 3& 2\\ 4& 1\end{vmatrix}\), then x is equal to:
1. 4
2. 8
3. 2
4. ±2√2
5. √2

Answer 1

Correct Answer - Option 4 : ±2√2

Calculation:

\(\rm \begin{vmatrix} 3&\rm x \\ \rm x&1 \end{vmatrix}=\begin{vmatrix} 3& 2\\ 4& 1\end{vmatrix}\)

⇒ 3 - x² = 3 - 8

⇒ x2 = 8

⇒ x = ±2√2.