# I need help

#### Canopus

I have two questions, they should be either true or false and I am asked to justify my answer.

#### DarnItJimImAnEngineer

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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#### Canopus

Thank you so much for the help!

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#### Canopus

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
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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Thank you Boss!