Calculate the product
[tex]\[
\left[\begin{array}{cc}0 & -1 \\ 5 & 4\end{array}\right]\left[\begin{array}{c}1 \\ 1\end{array}\right]
\][/tex]
and write your answer in simplest form.



Answer :

To calculate the product of the matrix [tex]\( A \)[/tex] and vector [tex]\( B \)[/tex], we need to perform matrix multiplication. Specifically, we'll multiply each row of matrix [tex]\( A \)[/tex] by vector [tex]\( B \)[/tex].

The matrix [tex]\( A \)[/tex] is:
[tex]\[ A = \begin{pmatrix} 0 & -1 \\ 5 & 4 \end{pmatrix} \][/tex]
The vector [tex]\( B \)[/tex] is:
[tex]\[ B = \begin{pmatrix} 1 \\ 1 \end{pmatrix} \][/tex]

For matrix multiplication, the resulting vector [tex]\( C \)[/tex] will be:
[tex]\[ C = A \cdot B \][/tex]

Now, let's calculate each element of the resulting vector [tex]\( C \)[/tex].

1. First element [tex]\( c_1 \)[/tex]:
[tex]\[ c_1 = 0 \cdot 1 + (-1) \cdot 1 = 0 - 1 = -1 \][/tex]

2. Second element [tex]\( c_2 \)[/tex]:
[tex]\[ c_2 = 5 \cdot 1 + 4 \cdot 1 = 5 + 4 = 9 \][/tex]

Putting these elements together, the resulting vector [tex]\( C \)[/tex] is:
[tex]\[ C = \begin{pmatrix} -1 \\ 9 \end{pmatrix} \][/tex]

So, the product of the given matrix and vector is:
[tex]\[ \begin{pmatrix} 0 & -1 \\ 5 & 4 \end{pmatrix} \begin{pmatrix} 1 \\ 1 \end{pmatrix} = \begin{pmatrix} -1 \\ 9 \end{pmatrix} \][/tex]

Therefore, the answer is:
[tex]\[ \begin{pmatrix} -1 \\ 9 \end{pmatrix} \][/tex]