Question 985432


The determinant of the 4x4 matrix of this system is equal to zero.


So, the matrix is singular, actually.


Therefore, it is not amazing that you found two solutions of the system. 


Indeed, there are infinitely many solutions. 



<U>The trick</U>: I did not calculate the determinant myself.


I simply asked GOOGLE, and it pointed me to this solver (online calculator):

http://ncalculators.com/matrix/4x4-matrix-determinant-calculator.htm 


I don't know why, but I trust to this result.