Question: Latihan
1 A: [ 2 -1 2
3 -2 1 ]
B: [ -1 2
-3 1
0 -2 ]
position_hint: center
Perkalian matriks dengan matriks
1. **Stating the problem:**
We are asked to multiply two matrices $$A$$ and $$B$$ where
$$A = \begin{bmatrix} 2 & -1 & 2 \\ 3 & -2 & 1 \end{bmatrix}$$ and
$$B = \begin{bmatrix} -1 & 2 \\ -3 & 1 \\ 0 & -2 \end{bmatrix}$$.
2. **Formula for matrix multiplication:**
If $$A$$ is an $$m \times n$$ matrix and $$B$$ is an $$n \times p$$ matrix, then the product $$AB$$ is an $$m \times p$$ matrix where each element is calculated as:
$$$(AB)_{ij} = \sum_{k=1}^n A_{ik} B_{kj}$$$
3. **Check dimensions:**
$$A$$ is $$2 \times 3$$ and $$B$$ is $$3 \times 2$$, so the product $$AB$$ is defined and will be a $$2 \times 2$$ matrix.
4. **Calculate each element of $$AB$$:**
- Element at position (1,1):
$$$(AB)_{11} = 2 \times (-1) + (-1) \times (-3) + 2 \times 0 = -2 + 3 + 0 = 1$$$
- Element at position (1,2):
$$$(AB)_{12} = 2 \times 2 + (-1) \times 1 + 2 \times (-2) = 4 - 1 - 4 = -1$$$
- Element at position (2,1):
$$$(AB)_{21} = 3 \times (-1) + (-2) \times (-3) + 1 \times 0 = -3 + 6 + 0 = 3$$$
- Element at position (2,2):
$$$(AB)_{22} = 3 \times 2 + (-2) \times 1 + 1 \times (-2) = 6 - 2 - 2 = 2$$$
5. **Final answer:**
$$AB = \begin{bmatrix} 1 & -1 \\ 3 & 2 \end{bmatrix}$$
This is the product of matrices $$A$$ and $$B$$.