# Math Help - Determinant

1. ## Determinant

Hello guys, can someone help me with this question please?

2. ## Re: Determinant

Originally Posted by Chipset3600
Hello guys, can someone help me with this question please?
$M=\left(\begin{array}{cccc} a & b & c & d \\ x & y & z & w \\ t & r & s & u \\ m & n & p & q\end{array}\right)$

$|M|=3$

$Q=\left(\begin{array}{cccc} 2 a & 10 b & 2 c & 2 d \\ x & 5 y & z & w \\ -t & -5 r & -s & -u \\ m & 5 n & p & q\end{array}\right)$

$|Q| = -10|M| = -30$

3. ## Re: Determinant

How did you get the -10?

4. ## Re: Determinant

Q & M are linearly dependent because you can obtain Q from M by:
1) 1st row x 2
2) 2nd col x5
3) 3rd row x (-1)

combined effect is -10 on determinant of M!

5. ## Re: Determinant

Thankkkkkkkkkkkk you! the problem was that i trought the Jacobbi theorem was only for Rows and not columns.