How do I solve these equations?

x2-2x3-x4=0
x1-x3-3x4=0
5x1+2x2+x4=0
2x1+3x2+x3+9x4=0
-x1+x2+4x4=0
x2+2x3+5x4=0

The numbers after x are all subscripts, lower cases. How do I solve these equations? At the end, x1=x2=x3=x4=0 should be the answer. Please show all your work step by step and tell me the right answer. Thanks.
2 answers 2