**4.9 SPM Practis (Soalan Pendek)**

**Soalan 1:**

$\left(\begin{array}{cc}1& 4\\ 6& 2\end{array}\right)+3\left(\begin{array}{cc}2& 0\\ 4& -3\end{array}\right)-\left(\begin{array}{cc}-3& 0\\ -2& -5\end{array}\right)=$

*Penyelesaian:*

$\begin{array}{l}\left(\begin{array}{cc}1& 4\\ 6& 2\end{array}\right)+3\left(\begin{array}{cc}2& 0\\ 4& -3\end{array}\right)-\left(\begin{array}{cc}-3& 0\\ -2& -5\end{array}\right)\\ =\left(\begin{array}{cc}1& 4\\ 6& 2\end{array}\right)+\left(\begin{array}{cc}6& 0\\ 12& -9\end{array}\right)-\left(\begin{array}{cc}-3& 0\\ -2& -5\end{array}\right)\\ =\left(\begin{array}{cc}7& 4\\ 18& -7\end{array}\right)-\left(\begin{array}{cc}-3& 0\\ -2& -5\end{array}\right)\\ =\left(\begin{array}{cc}7-(-3)& 4-0\\ 18-\left(-2\right)& -7-(-5)\end{array}\right)\\ =\left(\begin{array}{cc}10& 4\\ 20& -2\end{array}\right)\end{array}$
**Soalan 2:**

Cari nilai *m*dalam persamaan matriks berikut:

$\left(\begin{array}{cc}9& -4\\ 5& 0\end{array}\right)+\frac{1}{2}\left(\begin{array}{cc}8& m\\ 6& -10\end{array}\right)=\left(\begin{array}{cc}13& -7\\ -2& 1\end{array}\right)$

*Penyelesaian:*

$\begin{array}{l}\left(\begin{array}{cc}9& -4\\ 5& 0\end{array}\right)+\frac{1}{2}\left(\begin{array}{cc}8& m\\ 6& -10\end{array}\right)=\left(\begin{array}{cc}13& -7\\ -2& 1\end{array}\right)\\ -4+\frac{1}{2}m=-7\\ \frac{1}{2}m=-3\\ m=-6\end{array}$
**Soalan 3:**

$\begin{array}{l}\text{Diberi}\\ \left(\begin{array}{l}2x\\ 3y\end{array}\right)-4\left(\begin{array}{l}-2\\ 3\end{array}\right)=\left(\begin{array}{l}-2\\ 6\end{array}\right)\\ \text{Carinilai}x\text{dan}y.\end{array}$

*Penyelesaian:*

2*x* + 8 = –2

2*x* = –10

*x*= –5

3*y* – 12 = 6

3*y* = 18

*y*= 6

**Soalan 4:**

Diberi bahawa persamaan matriks 3(6 *m*) + *n*(3 4) = (12 7),

Cari nilai *m*+ *n*.

*Penyelesaian:*

3(6 *m*) + *n*(3 4) = (12 7)

18 + 3*n* = 12

3*n* = –6

*n*= –2

3*m* + 4*n* = 7

3*m* + 4(–2) = 7

3*m* = 15

*m*= 5

Maka *m* + *n* = 5 + (–2) = 3