Given that M={pmatrix} 3 & 2 \\ -1 & 4 {pmatrix} and N={pmatrix} 5 & 6 \\ -2 & -3 {pmatrix}, calculate (3 M-2 N)

Correct Answer is : (−1−6118){pmatrix} -1 & -6 \\ 1 & 18 {pmatrix}(−11−618)

{pmatrix} 1 & 6 \\ 1 & 18 {pmatrix}

{pmatrix} -1 & -6 \\ 1 & 18 {pmatrix}

{pmatrix} 1 & 6 \\ -1 & -18 {pmatrix}

{pmatrix} -1 & -6 \\ -1 & -18 {pmatrix}

Correct Answer is : (−1−6118){pmatrix} -1 & -6 \\ 1 & 18 {pmatrix}(−11−618)

Test Index

WAEC Further Mathematics 2021 Paper

Question : 3

Total: 38

Given that

M=\begin{pmatrix} 3 & 2 \\ -1 & 4 \end{pmatrix}

N=\begin{pmatrix} 5 & 6 \\ -2 & -3 \end{pmatrix}

(3 M-2 N)

Solution:

Concept:

Scalar multiplication of a matrix is done by multiplying each element by the scalar, followed by matrix subtraction element-wise.

Explanation:

First, find

3M

3M = 3\begin{pmatrix} 3 & 2 \\ -1 & 4 \end{pmatrix} = \begin{pmatrix} 9 & 6 \\ -3 & 12 \end{pmatrix}

Next, find

2N

2N = 2\begin{pmatrix} 5 & 6 \\ -2 & -3 \end{pmatrix} = \begin{pmatrix} 10 & 12 \\ -4 & -6 \end{pmatrix}

Now subtract:

3M - 2N = \begin{pmatrix} 9 & 6 \\ -3 & 12 \end{pmatrix} - \begin{pmatrix} 10 & 12 \\ -4 & -6 \end{pmatrix}

= \begin{pmatrix} 9 - 10 & 6 - 12 \\ -3 - (-4) & 12 - (-6) \end{pmatrix}

= \begin{pmatrix} -1 & -6 \\ 1 & 18 \end{pmatrix}

Answer:

\begin{pmatrix} -1 & -6 \\ 1 & 18 \end{pmatrix}

Therefore, the correct option is B.

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