hello everyone!

I have some questions about solving a system of equations by the Gaussian and Gauss-Jordan elimination methods.

1) how do i determine which method should i use for each system of equations?

2) using any of the two methods, do i have to do it by hand or is there a quicker way to do it (for example using a calculator)? If there is,how can i use my calculator for this? my calculator is a TI-84 plus.

3) how do i solve a system of equations with only the x variable. The variables for one of my systems of equations are x1, x2,x3,x4? Do i treat it as a system with x,y and z?

thank you so much