x 1-x2-x3+x4=0 ( 1)
x 1-x2-x3-3x4=0 (2)
x 1-x2-2x3+3x4=0 (3)
Solution:
( 1)-(2),4x4=0,x4=0。
x 1-x2-x3 = x 1-x2-2x 3 = 0,x3=0
So X 1-x2 = 0, x 1=x2,
The solution of the equation is: x 1=x2, x3=0, x4=0. x 1∈R,x2∈R .