How many kinds of solutions are there?

1 Answer
Jun 22, 2015

From the category in which this question is asked, I will assume you mean a finite linear system of equations. If such a system is in nn variables, then there are n + 2n+2 kinds of solutions.

Explanation:

If a linear system involves nn variables, x_1, x_2,..x_nx1,x2,..xn, then the solution set will take one of the following n + 2n+2 forms:

(0) The empty set. The system is inconsistent and has no solutions.
(1) A unique solution in the form of an nn-tuple
(2) A line of solutions expressible as:

x_1 = a_1*t + b_1x1=a1t+b1
x_2 = a_2*t + b_2x2=a2t+b2
...
x_n = a_n*t + b_nxn=ant+bn

for all t in RR

(3) A plane of solutions expressible as:

x_1 = a_1*t_1 + b_1*t_2 + c_1
x_2 = a_2*t_1 + b_2*t_2 + c_2
...
x_n = a_n*t_1 + b_n*t_2 + c_n

for all (t_1, t_2) in RR xx RR

...
(n+1) The whole of RR^n