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5 Common Mistakes Students Make When Solving Matrices Questions in O-Level Math


Matrices Questions

Matrices are a fundamental part of mathematics, especially for students in the upper secondary level. However, students often make common mistakes when tackling matrices questions. This article will highlight five prevalent errors and provide strategies to avoid them.


1. Not Paying Attention to Matrix Dimensions

This occurs when students forget to check whether matrix operations like addition, subtraction or multiplication are valid based on the dimensions of the matrices involved. 


Addition/Subtraction of Two Matrices


One of the most frequent mistakes students make is neglecting to check the dimensions of matrices before performing operations. For addition or subtraction to be valid, the matrices involved must have the same order, meaning they must have the same number of rows and number of columns. Only when matrices share identical dimensions can the addition or subtraction be carried out correctly. This oversight can lead to significant errors, so it's crucial to always verify matrix dimensions before attempting these operations. 

Not Paying Attention to Matrix Dimensions

Addition/Subtraction of Two Matrices

Multiplication of Two Matrices


For matrix multiplication to be possible, the number of columns in the first matrix must equal the number of rows in the second matrix. Students often overlook this requirement, leading to mistakes in their calculations.

Multiplication of Two Matrices

2. Misunderstanding Matrix Multiplication


Non-Commutative Nature

A common misconception is treating matrix multiplication as commutative, assuming that AB = BA. However, matrix multiplication is not commutative; AB is not necessarily equal to BA. This misunderstanding can lead to incorrect results.


Associative Property

Despite the non-commutative property, matrix multiplication is associative, meaning A(BC) = (AB)C. Understanding this property is crucial for correctly solving matrices practice questions.


3. Forgetting the Identity Matrix


When tackling problems that involve matrix multiplication, students might overlook the existence or properties of the identity matrix, a special type of square matrix. Many students fail to recognise the potential to use the identity matrix effectively, such as multiplying a matrix by the identity matrix to obtain the original matrix.


Misunderstanding Matrix Multiplication

4. Not Following the Order of Operations


Just like arithmetic operations, matrix operations must adhere to specific rules regarding the order of operations. Students who do not perform these operations in the correct sequence will end up with incorrect results. For instance, since multiplication takes precedence over addition or subtraction, scalar multiplication must be completed before adding or subtracting matrices.


5. Ignoring Scalar Multiplication


Scalar multiplication involves multiplying each element of a matrix by a scalar (a single number). Students might sometimes forget to perform scalar multiplication or apply it incorrectly, resulting in errors in their solutions. 


The correct method of multiplying a matrix by a scalar is as follows:

Ignoring Scalar Multiplication

Understanding and avoiding these common mistakes is crucial for mastering matrices questions in the O-level Math exam. Students must pay attention to matrix dimensions, correctly apply matrix multiplication, remember the identity matrix, follow the correct order of operations, and not ignore scalar multiplication.


Not Following the Order of Operations

Thorough practice with matrices practice questions and matrices extra questions is essential. Students should solve a variety of problems, including skew symmetric and singular matrix problems, to prepare adequately for board examinations.

By focusing on these areas, students can improve their proficiency in solving matrices questions, ensuring they are well-prepared for their exams.


As parents of secondary students, consider to enrol them in AGrader Learning Centre's Secondary Math tuition. Our programme is designed to enhance students' skills in recognising and solving various types of exam questions. We provide structured notes, exercises, and clear examples to ensure thorough mastery of mathematical concepts. 


Thorough practice with matrices practice questions and matrices extra questions is essential

AGrader Learning Secondary Maths tuition emphasises strategic exam techniques, helping students avoid common mistakes and mastering exam answering techniques. Additionally, we offer the exclusive EverLoop Improvement System for unlimited after-class revision sessions, both in-person and online, to address learning gaps. This comprehensive support system is complimentary for AGrader students.


Enrol your child in AGrader Learning Centre today and give them the advantage they need to excel in their exams. Sign up now to secure their spot and benefit from our unparalleled support and resources!


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