Pergunta
Solve the system of equations using Gaussian elimination or Gauss-Jordan elimination. Use a graphing calculator to check your answer. 2x-11y-3z=3 x+2y+z=-1 6x-9y-z=1 Select the correct choice below and, if necessary.fill in the answer box(es) to complete your choice. A. There is one solution. The solution is (square cdot square cdot square ) (Type integers or simplified fractions.) B. There are infinitely many solutions. The solutions are of the form (square ,square ,z) , where z is any real number. square (Simplify your answers. Use integers or fractions for any numbers in the expression.) C. There is no solution.
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JosielProfissional · Tutor por 6 anos
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To solve the system of equations using Gaussian elimination or Gauss-Jordan elimination, we first write the augmented matrix for the system:<br /><br />\[<br />\begin{pmatrix}<br />2 & -11 & -3 & | & 3 \\<br />1 & 2 & 1 & | & -1 \\<br />6 & -9 & -1 & | & 1<br />\end{pmatrix}<br />\]<br /><br />We will perform row operations to transform this matrix into reduced row echelon form.<br /><br />Step 1: Make the leading coefficient of the first row 1 (if it is not already). In this case, it is already 1 in the second row, so we can swap the first and second rows:<br /><br />\[<br />\begin{pmatrix}<br />1 & 2 & 1 & | & -1 \\<br />2 & -11 & -3 & | & 3 \\<br />6 & -9 & -1 & | & 1<br />\end{pmatrix}<br />\]<br /><br />Step 2: Eliminate the x-term from the second and third rows by subtracting appropriate multiples of the first row:<br /><br />Row 2 = Row 2 - 2 * Row 1:<br />\[<br />\begin{pmatrix}<br />1 & 2 & 1 & | & -1 \\<br />0 & -15 & -5 & | & 5 \\<br />6 & -9 & -1 & | & 1<br />\end{pmatrix}<br />\]<br /><br />Row 3 = Row 3 - 6 * Row 1:<br />\[<br />\begin{pmatrix}<br />1 & 2 & 1 & | & -1 \\<br />0 & -15 & -5 & | & 5 \\<br />0 & -21 & -7 & | & 7<br />\end{pmatrix}<br />\]<br /><br />Step 3: Make the leading coefficient of the second row 1 by dividing the entire row by -15:<br /><br />\[<br />\begin{pmatrix}<br />1 & 2 & 1 & | & -1 \\<br />0 & 1 & \frac{1}{3} & | & -\frac{1}{3} \\<br />0 & -21 & -7 & | & 7<br />\end{pmatrix}<br />\]<br /><br />Step 4: Eliminate the y-term from the first and third rows by adding appropriate multiples of the second row:<br /><br />Row 1 = Row 1 - 2 * Row 2:<br />\[<br />\begin{pmatrix}<br />1 & 0 & \frac{1}{3} & | & -\frac{1}{3} \\<br />0 & 1 & \frac{1}{3} & | & -\frac{1}{3} \\<br />0 & -21 & -7 & | & 7<br />\end{pmatrix}<br />\]<br /><br />Row 3 = Row 3 + 21 * Row 2:<br />\[<br />\begin{pmatrix}<br />1 & 0 & \frac{1}{3} & | & -\frac{1}{3} \\<br />0 & 1 & \frac{1}{3} & | & -\frac{1}{3} \\<br />0 & 0 & 0 & | & 0<br />\end{pmatrix}<br />\]<br /><br />Step 5: Make the leading coefficient of the third row 1 (if necessary) and eliminate the z-term from the first and second rows. However, since the third row is all zeros, we can skip this step.<br /><br />The resulting matrix corresponds to the following system of equations:<br /><br />\[<br />\begin{cases}<br />x + \frac{1}{3}z = -\frac{1}{3} \\<br />y + \frac{1}{3}z = -\frac{1}{3} \\<br />0 = 0<br />\end{cases}<br />\]<br /><br />This indicates that there are infinitely many solutions. We can express \(x\) and \(y\) in terms of \(z\):<br /><br />\[<br />x = -\frac{1}{3} - \frac{1}{3}z<br />\]<br />\[<br />y = -\frac{1}{3} - \frac{1}{3}z<br />\]<br /><br />Thus, the solutions are of the form \((-\frac{1}{3} - \frac{1}{3}z, -\frac{1}{3} - \frac{1}{3}z, z)\), where \(z\) is any real number.<br /><br />Therefore, the correct choice is:<br /><br />B. There are infinitely many solutions. The solutions are of the form \((- \frac{1}{3} - \frac{1}{3}z, - \frac{1}{3} - \frac{1}{3}z, z)\), where \(z\) is any real number.
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