Chapter 2 - Systems of Linear Equations - 2.1 Introduction to Systems of Linear Equations - Exercises 2.1 - Page 63: 23

$(x_1,x_2,x_3,x_4)=(5,-2,1,1)$

Consider $x_4=1$ and $x_3-x_4=0 \implies x_3-(1)=0 $ or, $x_3=1$ Now, $x_2+x_3+x_4=0 \implies x_2+1+1=0$ or, $x_2=--2$ and $x_1+x_2-x_3-x_4=0 \implies x_1+ (-2)-1-1=0$ or, $x_1=5$ Our result is : $(x_1,x_2,x_3,x_4)=(5,-2,1,1)$