Not a specially question but I am really bad at them so I would want to know if there is any quick ways or methods to do them except technology. Or like any ways to check the answers as I seem to get various answers
Just for example, how to do
1 2 1
2 -3 4
Those different colors are the ones equal to!
Like for that example how do you know that you cannot go any further(no solutions))
Please help, i need quick ways to do and check