1. The solution is k (x 1-x2), and x 1 and x2 are the solutions of the corresponding nonhomogeneous equation, that is, it consists of the general solution of the corresponding homogeneous equation and the special solution of the nonhomogeneous equation. After subtraction, it is the general solution of homogeneous equation, and k is any non-zero number.

2. (A-E)(B-E)=E can be deduced from the original formula, so both A-E and B-E are reversible.

3. If R(A)+R(B) is less than or equal to R(AB)+3, and b is a non-zero matrix, and it is known that R(B) is greater than or equal to 1, then R(A) is less than or equal to 2, so AX=0 has a non-zero solution, so D is selected.

4. The matrix they form is transformed into rows, and the quality of submatrix and matrix is the largest independent group. Find the representation of other vectors by transforming yourself. This question is so troublesome that I won't tell you the result.

Hehe, come on! I wish you progress in your study!