1. Explain why vectors QR and RQ are not equivalent.

2. Explain in your own words when the elimination method for solving a system of equations is preferable to the substitution method.

I have attempted to answer the questions but am wishing to see if done correctly and am also looking for examples if possible. I vaguely understand the concept but am in need examples for clarification.

1 - Vectors are defined or measured by their magnitude and length. So for two vectors to be equivalent they in turn need to have the same length and direction. However, vectors QR and RQ are in opposite direction thereby causing them not to be equivalent.

2 - If there is a problem with a large number of equations and variables then the elimination method would be preferable to the substitution method. After all, it would break down the problem and/or equations in an easier manner.