**4.9 SPM Practis (Kertas 1)**

**Soalan 5:**

Diberi bahawa $(3\text{}x)\left(\begin{array}{l}x\\ -1\end{array}\right)=\left(18\right),$
cari nilai

*x*.

*Penyelesaian:*

$(3\text{}x)\left(\begin{array}{l}x\\ -1\end{array}\right)=\left(18\right)$

[3 ×

*x*+*x*(–1)] = (18)3

*x*–*x*= 182

*x*= 18

*x***= 9**

**Soalan 6:**

*Penyelesaian:***Soalan 7:**

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

*Penyelesaian:*$=\left(\overline{)3}\times 2\right)\left(2\times \overline{)1}\right)=\left(\overline{)3\times 1}\right)$

$\begin{array}{l}\left(\begin{array}{cc}2& 4\\ \begin{array}{l}-3\\ 4\end{array}& \begin{array}{l}0\\ 1\end{array}\end{array}\right)\left(\begin{array}{l}1\\ -3\end{array}\right)=\left(\begin{array}{l}2\left(1\right)+4\left(-3\right)\\ \left(-3\right)\left(1\right)+0\left(-3\right)\\ \left(4\right)\left(1\right)+1\left(-3\right)\end{array}\right)\\ \text{}=\left(\begin{array}{l}2-12\\ -3+0\\ 4-3\end{array}\right)\\ \text{}=\left(\begin{array}{l}-10\\ -3\\ 1\end{array}\right)\end{array}$

**Soalan 8:**

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

*Penyelesaian:*Peringkat hasil darab dua matriks

$=\left(\overline{)1}\times 3\right)\left(3\times \overline{)2}\right)=\left(\overline{)1\times 2}\right)$

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

= (1×5 + (–1)(–3) + (2)(2) 1×1 + (–1)(0) + (2)(4))

= (5 + 3 + 4 1 + 0 + 8)

= (12 9)