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The determinant of the matrix $$\begin{bmatrix}2 &0  &0  &0 \\  8&  1&  7& 2\\  2&  0&2  &0 \\  9&0  & 6 & 1 \end{bmatrix}$$

  1. $4$
  2. $0$
  3. $15$
  4. $20$
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32 votes
$\text{Let }|A|=\begin{vmatrix}2 &0  &0  &0 \\  8&  1&  7& 2\\  2&  0&2  &0 \\  9&0  & 6 & 1 \end{vmatrix}$

$\implies |A|=2\times\begin{vmatrix}  1&  7& 2\\  0&2  &0 \\ 0  & 6 & 1 \end{vmatrix}$

$\implies |A|=2\times 1\times \begin{vmatrix}  2  &0 \\ 6 & 1 \end{vmatrix}$

$\implies |A|=2\times 1\times (2-0)$

$\implies |A|=2\times 1\times 2=4$

Answer$: A$
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2*1*2*1=4 break it into determinant of smaller pieces where you are doing it in such a way that you should have to do lesser number of operations
Answer:

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If the matrix $A$ is such that $$A= \begin{bmatrix} 2\\ −4\\7\end{bmatrix}\begin{bmatrix}1& 9& 5\end{bmatrix}$$ then the determinant of $A$ is equal to ______.