m 개의 equation 과 n 개의 decision variable 이 있다고 할 때, If m > n, there will be m−n redundant equations which can be eliminated (필요없는 eq 들이 존재하는 것) If n = m, there will be an unique solution or there may not be any solution, If n < m, a case of undetermined set of linear equations, if they have any solution, there may be innumerable solutions