Matrix
matrix is a rule of writing or presenting data consisting of rows and columns in an open or closed parenthesis.
• the problem above is about matrix multiplication
the first type of multiplication :
if k is a constant and A is a matrix, then kA can be operated by multiplying each element of matrix A by the constant k.
ex : 3[-1 2 2] = [-3 6 6]
multiplication of two matrices :
the multiplication of a 1x n matrix and a n × 1 column matrix is a 1 × 1 matrix.
the above problem using matrices of 3 × 1 and 1 × 3 size will produce a 3 × 3 matrix.
Answer :
| 3 | | 9 |
3|19| [-1 -3 -5] =|57| [-1 -3 -5]
|12| |36|
| 9×(-1) 9×(-3) 9×(-5) |
= | 57×(-1) 57×(-3) 57×(-5)|
| 36×(-1) 36×(-3) 36×(-5)|
| -9 -27 -45 |
= | -57 -171 -285|
| -36 -108 -180|
