I don't understand the asepcts of matrices infinite. Let say I have 3 x 3 matrix A = [ (A1) 2 3; 2 3 4; 4 4 5 ] b = [ (b1); 2; 3] I want to find all three conditions: case 1 det =/ 0 - > unique solution case 2 det = 0, no solution case 3 infinite solution I am actually writing a program for these 3 cases. I am only allow to change A1 and b2 (they are variables). I know how to program them. But what I don't understand is the concept of matrices in terms of the 3 cases. Can someone explains, how does one gets case 3? i see how case 2 you can use det to determine something solution or no solution. what about case 3?