Система х1+х2-2х3=-1
Х1+2х2+3х3=0
4х4+5х2-2х3=-3

система х1+х2-2х3 = -1

               х1+2х2+3х3 = 0

                4х1+5х2-2х3 = -3

система  х1 = 2х3-х2-1

                2х3-х2-1+2х2+3х3 = 0

                4(2х3-х2-1)+5х2-2х3 = -3

система  х1 = 2х3-х2-1

                5х3+х2-1 = 0

                8х3-4х2-4+5х2-2х3 = -3

система  х1 = 2х3-х2-1

                5х3+х2 = 1

                 6х3+х2 = 1

система  х1 = 2х3-х2-1

                х2 = 1-5х3

               6х3+1-5х3 = 1

система  х1 = 2х3-х2-1

                х2 = 1-5х3

                х3 = 0

система  х1 = -х2-1

               х2 = 1-5*0

                х3 = 0

система   х1 = -1-1

                 х2 = 1

                 х3 = 0

система  х1 = -2

                х2 = 1

                х3 = 0