Select the correct answer.

If the row echelon form of a system of three linear equations in three variables is given by this matrix, which phrase describes the solutions?

[tex]$\left[\begin{array}{lll|l}1 & 0 & 0 & 1 \\ 0 & 1 & 0 & 3 \\ 0 & 0 & 0 & 7\end{array}\right]$[/tex]

A. one solution at the point [tex]$(1,3,7)$[/tex]

B. infinite number of solutions

C. no solutions

D. one solution at the point [tex]$(1,3,0)$[/tex]



Answer :

To determine the nature of the solutions for a system of linear equations given in row echelon form, we analyze the augmented matrix provided:

[tex]\[ \left[\begin{array}{lll|l}1 & 0 & 0 & 1 \\ 0 & 1 & 0 & 3 \\ 0 & 0 & 0 & 7\end{array}\right] \][/tex]

Each row in this matrix corresponds to a linear equation. Let's translate each row into its corresponding equation:

1. The first row is [tex]\(1x + 0y + 0z = 1\)[/tex], meaning:
[tex]\[ x = 1 \][/tex]

2. The second row is [tex]\(0x + 1y + 0z = 3\)[/tex], meaning:
[tex]\[ y = 3 \][/tex]

3. The third row is [tex]\(0x + 0y + 0z = 7\)[/tex], which translates to:
[tex]\[ 0 = 7 \][/tex]

The third equation, [tex]\(0 = 7\)[/tex], is a contradiction because it is not possible for zero to equal seven. This indicates that there is no set of values for [tex]\(x\)[/tex], [tex]\(y\)[/tex], and [tex]\(z\)[/tex] that will satisfy this system of equations.

Therefore, the system of equations has no solutions.

The correct answer is:
C. no solutions