Answer
No solution.
Work Step by Step
Write the augmented matrix and,
using row transformations arrive at the reduced row echelon form.
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It was suggested to use technology for some problems...
Syntax for matrix input:
A:={{1, 1, -1, -2},{1, -1, -7, 0},{ 2/7, 0, -8/7, 14}}
In the input box, begin typing "Red..."
select the function:
ReducedRowEchelonForm(A)
(see screenshot)
The last row represents the equation
0 = 1,
so the system is inconsistent.
No solution.