Please check my solution for a matrices and determinants problem

[msd1997]

 

[pka]

View attachment 27136

HERE is a tool to check your work.

 

[msd1997]

HERE is a tool to check your work.

Thank you, but can you please tell me if my method is correct?
I cannot access the "step by step" solution on wolframalpha. It's behind a paywall.

 

[Levido]

It's behind a paywall.

Here's a tip. Buy the app on the app/play store. It's a one time fee (2.99 USD at the moment) and you'll get full step by step solutions forever for most high school maths problems. If you plan on studying maths it's by far the best value investment you could make.

Plus it shows a little support for them and their service.