If $\begin{vmatrix}2 & 3 & 2\\x & x & x\\4 & 9 & 1\end{vmatrix}+3=0$ then the value of x is : |
1 -1 0 3 |
-1 |
Given determinant equation: $\left| \begin{matrix} 2 & 3 & 2 \\ x & x & x \\ 4 & 9 & 1 \end{matrix} \right| + 3 = 0$ Compute the determinant using cofactor expansion along the first row: $|A| = 2 \begin{vmatrix} x & x \\ 9 & 1 \end{vmatrix} - 3 \begin{vmatrix} x & x \\ 4 & 1 \end{vmatrix} + 2 \begin{vmatrix} x & x \\ 4 & 9 \end{vmatrix}$ Compute 2×2 determinants: $\begin{vmatrix} x & x \\ 9 & 1 \end{vmatrix} = x*1 - x*9 = -8x$ $\begin{vmatrix} x & x \\ 4 & 1 \end{vmatrix} = x*1 - x*4 = -3x$ $\begin{vmatrix} x & x \\ 4 & 9 \end{vmatrix} = x*9 - x*4 = 5x$ Substitute back: $|A| = 2(-8x) - 3(-3x) + 2(5x) = -16x + 9x + 10x = 3x$ Set $|A| + 3 = 0$: $3x + 3 = 0 \Rightarrow 3x = -3 \Rightarrow x = -1$ Answer: $x = -1$ |