Please explain why x4 was set equal to one 6 Suppose the mat

Please explain why x4 was set equal to one

6. Suppose the matrix equation Ax b is row-equivalent to the reduced augmented matrix b 1s row-equuivalel 1 0 2 0 1 0 00 1 1 Find the solution of the linear system.

Solution

from the third row

it states that 0x₁+0x₂+0x₃+1x₄=1

so x₄=1