*MATHEMATICS FORM 4: MATRICES - SIMPLIFIED KCSE REVISION NOTES*
*By: Form 4 Student - Kenya (2026) - 8 Pages*
*1. INTRODUCTION*
A matrix is a rectangular arrangement of numbers in rows and columns. We write order as m
x n.
Example:
A=|1 2 3|
|4 5 6|
This is order 2x3 (2 rows, 3 columns)
*2. TYPES*
a) Row Matrix: [1 2 3] - only 1 row
b) Column Matrix: |1| - only 1 column
|2|
c) Square Matrix: Same rows and columns e.g 2x2
d) Zero Matrix: All elements zero
e) Identity Matrix I = |1 0|
|0 1|
*3. ADDITION & SUBTRACTION*
Rule: Only same order.
Example:
A = |2 3| B = |1 4|
|1 2| |3 2|
A+B = |2+1 3+4| = |3 7|
|1+3 2+2| |4 4|
*4. MULTIPLICATION BY SCALAR*
2 x |1 2| = |2 4|
|3 4| |6 8|
*5. MULTIPLICATION OF TWO MATRICES*
Example:
A = |2 1| B = |3 1|
|1 2| |2 3|
A x B = | (2_3+1_2) (2_1+1_3) | = |8 5|
| (1_3+2_2) (1_1+2_3) | |7 7|
*6. DETERMINANT (2x2 only for KCSE)*
If A = |a b|
|c d|
*By: Form 4 Student - Kenya (2026) - 8 Pages*
*1. INTRODUCTION*
A matrix is a rectangular arrangement of numbers in rows and columns. We write order as m
x n.
Example:
A=|1 2 3|
|4 5 6|
This is order 2x3 (2 rows, 3 columns)
*2. TYPES*
a) Row Matrix: [1 2 3] - only 1 row
b) Column Matrix: |1| - only 1 column
|2|
c) Square Matrix: Same rows and columns e.g 2x2
d) Zero Matrix: All elements zero
e) Identity Matrix I = |1 0|
|0 1|
*3. ADDITION & SUBTRACTION*
Rule: Only same order.
Example:
A = |2 3| B = |1 4|
|1 2| |3 2|
A+B = |2+1 3+4| = |3 7|
|1+3 2+2| |4 4|
*4. MULTIPLICATION BY SCALAR*
2 x |1 2| = |2 4|
|3 4| |6 8|
*5. MULTIPLICATION OF TWO MATRICES*
Example:
A = |2 1| B = |3 1|
|1 2| |2 3|
A x B = | (2_3+1_2) (2_1+1_3) | = |8 5|
| (1_3+2_2) (1_1+2_3) | |7 7|
*6. DETERMINANT (2x2 only for KCSE)*
If A = |a b|
|c d|
