I'm stuck in this question :
\begin{bmatrix} x & 4 & -1 \end{bmatrix} \begin{bmatrix} 2 & 1 & 0\\ 1 & 0 & 2\\ 0 & 2 & 4 \end{bmatrix} \begin{bmatrix} x\\ 4\\ 1 \end{bmatrix}
The product of the above 3 matrices equals O. The result of the product comes out to be :
\begin{bmatrix} 2x^2+4x & 4x-8 & -4 \end{bmatrix}
Since this is equal to O, which is a null matrix, I did:
2x^2 + 4x = 0
4x - 8 = 0
However this cannot be possible as -4=!0
What am I doing wrong here?
The correct option seems to be: x = -2 +- \sqrt{10}
@Bye_World, thanks for the answer.
I had a brain malfunction I suppose.
[1x3] * [3x1] is a [1x1] matrix
Hence, the result is 2x^2 + 8x -4 = 0