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Math

Math Snap

PROBLEM

Do the vectors v1=[003]\mathbf{v}_{1} = \begin{bmatrix} 0 \\ 0 \\ -3 \end{bmatrix}, v2=[056]\mathbf{v}_{2} = \begin{bmatrix} 0 \\ -5 \\ 6 \end{bmatrix}, and v3=[539]\mathbf{v}_{3} = \begin{bmatrix} 5 \\ -3 \\ 9 \end{bmatrix} span $\mathbb{R}^{3$? Explain.

STEP 1

Assumptions1. The vectors are $\mathbf{v}_{1}=\left[\begin{array}{r} 0 \\ 0 \\ -3\end{array}\right], \mathbf{v}_{}=\left[\begin{array}{r}
0 \\
-5 \\
6\end{array}\right]and and \mathbf{v}_{3}=\left[\begin{array}{r}
5 \\
-3 \\
9\end{array}\right]$
. We need to determine if these vectors span R3\mathbb{R}^{3}
3. Spanning R3\mathbb{R}^{3} means that any vector in R3\mathbb{R}^{3} can be written as a linear combination of these vectors.

STEP 2

We will first write these vectors as the columns of a matrix AA.
A=[0050569]A = \begin{bmatrix} 0 &0 &5 \\ 0 & -5 & - \\ - &6 &9\end{bmatrix}

STEP 3

To determine if the vectors span R3\mathbb{R}^{3}, we need to find the rank of the matrix AA. The rank of a matrix is the maximum number of linearly independent rows or columns. If the rank of the matrix is3, then the vectors span R3\mathbb{R}^{3}.

STEP 4

We will perform Gaussian elimination to find the row echelon form of the matrix. We start by swapping the first and third rows to bring a non-zero element to the top.
A=[3690300]A = \begin{bmatrix} -3 &6 &9 \\ 0 & - & -3 \\ 0 &0 &\end{bmatrix}

STEP 5

Next, we multiply the first row by 13-\frac{1}{3} to make the leading element of the first row1.
A=[123053005]A = \begin{bmatrix} 1 & -2 & -3 \\ 0 & -5 & -3 \\ 0 &0 &5\end{bmatrix}

STEP 6

Then, we multiply the second row by 15-\frac{1}{5} to make the leading element of the second row1.
A=[1230135005]A = \begin{bmatrix} 1 & -2 & -3 \\ 0 &1 & \frac{3}{5} \\ 0 &0 &5\end{bmatrix}

STEP 7

Finally, we multiply the third row by 15\frac{1}{5} to make the leading element of the third row1.
A=[1230135001]A = \begin{bmatrix} 1 & -2 & -3 \\ 0 &1 & \frac{3}{5} \\ 0 &0 &1\end{bmatrix}

SOLUTION

Now that we have the row echelon form of the matrix, we can see that the rank of the matrix is3, since there are3 non-zero rows. This means that the vectors v1,v2,v3\mathbf{v}_{1}, \mathbf{v}_{2}, \mathbf{v}_{3} span R3\mathbb{R}^{3}.
So, the correct answer is D. Yes. When the given vectors are written as the columns of a matrix A,AA, A has a pivot position in every row.

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