I need help

Jul 2019
4
1
Saudi Arabia
I have two questions, they should be either true or false and I am asked to justify my answer.



Thank you in advance.
 
Jun 2019
493
260
USA
Q1) A square matrix is singular if its determinant is zero (and vice versa). Find the determinant and see whether it equates to zero for all a, b, c.

Q2) If I recall correctly, |AB| is equal to |A||B|. If that's true, then |B| = (|P|/|P|)|A| = |A|.
 
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Jul 2019
4
1
Saudi Arabia
Hello, for Q1) My friend had the solution below:


How did he come to this solution? I have tried to calculate the determinant but the unknowns made it a headache for me.
 

romsek

Math Team
Sep 2015
2,753
1,534
USA
Hello, for Q1) My friend had the solution below:


How did he come to this solution? I have tried to calculate the determinant but the unknowns made it a headache for me.
It's just standard Gaussian elimination

 

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