Given [tex]\( A=\left[\begin{array}{ll}1 & 4 \\ 2 & 3\end{array}\right] \)[/tex] and [tex]\( B=\left[\begin{array}{ll}-4 & -1 \\ -3 & -2\end{array}\right] \)[/tex]:

(a) Find the matrix [tex]\( 2A + B \)[/tex].

(b) Find a matrix [tex]\( C \)[/tex] such that [tex]\( C + B = \left[\begin{array}{ll}0 & 0 \\ 0 & 0\end{array}\right] \)[/tex].



Answer :

Certainly! Let's tackle the problem step-by-step.

Given the matrices:

[tex]\[ A = \begin{pmatrix} 1 & 4 \\ 2 & 3 \end{pmatrix} \][/tex]

[tex]\[ B = \begin{pmatrix} -4 & -1 \\ -3 & -2 \end{pmatrix} \][/tex]

### Part (a) Find the matrix [tex]\(2A + B\)[/tex]

First, we compute [tex]\( 2A \)[/tex]:

[tex]\[ 2A = 2 \begin{pmatrix} 1 & 4 \\ 2 & 3 \end{pmatrix} = \begin{pmatrix} 2 \cdot 1 & 2 \cdot 4 \\ 2 \cdot 2 & 2 \cdot 3 \end{pmatrix} = \begin{pmatrix} 2 & 8 \\ 4 & 6 \end{pmatrix} \][/tex]

Next, add matrix [tex]\( B \)[/tex] to [tex]\( 2A \)[/tex]:

[tex]\[ 2A + B = \begin{pmatrix} 2 & 8 \\ 4 & 6 \end{pmatrix} + \begin{pmatrix} -4 & -1 \\ -3 & -2 \end{pmatrix} = \begin{pmatrix} 2 + (-4) & 8 + (-1) \\ 4 + (-3) & 6 + (-2) \end{pmatrix} \][/tex]

Performing the addition element-wise:

[tex]\[ 2A + B = \begin{pmatrix} -2 & 7 \\ 1 & 4 \end{pmatrix} \][/tex]

### Part (b) Find a matrix [tex]\(C\)[/tex] such that [tex]\(C + B = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix}\)[/tex]

To solve for [tex]\(C\)[/tex], we start from the equation:

[tex]\[ C + B = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix} \][/tex]

Subtract [tex]\( B \)[/tex] from both sides to isolate [tex]\( C \)[/tex]:

[tex]\[ C = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix} - B \][/tex]

Substitute [tex]\( B \)[/tex] into the equation:

[tex]\[ C = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix} - \begin{pmatrix} -4 & -1 \\ -3 & -2 \end{pmatrix} \][/tex]

Subtract [tex]\( B \)[/tex] element-wise:

[tex]\[ C = \begin{pmatrix} 0 - (-4) & 0 - (-1) \\ 0 - (-3) & 0 - (-2) \end{pmatrix} = \begin{pmatrix} 4 & 1 \\ 3 & 2 \end{pmatrix} \][/tex]

Therefore, the matrix [tex]\( C \)[/tex] that satisfies [tex]\(C + B = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix}\)[/tex] is:

[tex]\[ C = \begin{pmatrix} 4 & 1 \\ 3 & 2 \end{pmatrix} \][/tex]

### Final Summary

(a) The matrix [tex]\(2A + B\)[/tex] is:

[tex]\[ \begin{pmatrix} -2 & 7 \\ 1 & 4 \end{pmatrix} \][/tex]

(b) The matrix [tex]\(C\)[/tex] such that [tex]\(C + B = \begin{pmatrix} 0 & 0 \\ 0 & 0 \end{pmatrix}\)[/tex] is:

[tex]\[ \begin{pmatrix} 4 & 1 \\ 3 & 2 \end{pmatrix} \][/tex]