CBSE Ch 4 Important Questions Class 12 Maths 2025 PDF

Determinants form a very important part of the Class 12 Mathematics curriculum, and mastery of this topic helps in understanding many concepts in linear algebra, matrices, and even advanced mathematics. We will discuss here some of the important questions and concepts related to determinants with an emphasis on topics most likely to appear in Class 12 exams. Familiarity with these questions will not only help the students score better but will also enhance their overall understanding of the subject.

Maths Chapter 4 is very important for the students as many questions are framed from this chapter in board examinations. In CBSE Class 12 Maths Chapter 4 Important Questions, you understand the various important concepts like Determinant Definition, properties, area of a Triangle, minors and cofactors, adjoint and the inverse of a matrix, determinants, and matrix applications.

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What is a Determinant?

Before discussing important questions on determinants, it is important to know the definition. A determinant is a scalar quantity derived from the elements of a square matrix, which carry some features regarding that matrix. It is represented by det(A) or |A|, in which A refers to the given matrix in a question. The determinant is an important term that tells about the invertibility of the matrix and gives some information about the geometric properties of the transformations.

Properties of Determinants

Important properties of determinants, which every student must know, are as follows:

  • The determinant of a matrix is zero if and only if it is singular (non-invertible).
  • Interchanging any two rows or columns changes the sign of the determinant.
  • If any two rows (or columns) of a matrix are the same, then the determinant is zero.
  • If each entry in a row or column of a determinant is multiplied by a scalar, then the determinant itself is multiplied by that scalar.

Key Topics and Important Questions

In this section, we will cover the key topics and the important questions on the Class 12 determinants.

Evaluation of Determinants

The problem that students generally face while solving the determinants chapter is finding a matrix determinant, especially for 3×3 and larger matrices. To be successful in this area, students need to master the cofactor expansion method and row or column operations.

Properties and Applications of Determinants

A large proportion of the exam questions test the student's understanding of properties of determinants, particularly in terms of showing whether a matrix is singular or nonsingular and in using determinants to solve systems of linear equations.

Inverse of a Matrix Using Determinants

Another important application for which determinants are essential is in finding the inverse of a matrix. A matrix is invertible if and only if its determinant is non-zero.

Important Questions 

Here are some of the Important questions on Determinants.

1. Given the matrix: A = [ 2  1  3 ] 

                                       [ 4  1  2 ]

                                       [ 6  1  4 ]

Find det(A) using cofactor expansion along the first row.

2. Given the matrix: A = [ 1  2  3  4 ]

                                      [ 0  1  2  3 ]

                                      [ 1  0  1  2 ]

                                      [ 2  1  0  1 ]

Find det(A) using cofactor expansion along the first row.

3. If A = [ 2  1  3 ]

             [ 4  1  3 ]

             [ 6  1  3 ]

Prove that det(A) = 0.

4. Consider the matrix: A = [ 2  1  1 ]

                                           [ 3  2  1 ]

                                           [ 1  1  1 ]

Perform a row operation like R2 -> R2 - 3R1 and calculate the new determinant.

5. A = [ 1  2 ]

          [ 3  4 ]

Find A⁻¹ using the determinant method.

6. Given the vertices A(1, 2), B(4, 6), and C(7, 8), use determinants to find the area of the triangle.

7.   Given the matrix: A =[ 1  2  3 ]

                                       [ 0  1  4 ]

                                       [ 5  6  0 ]

Find A{-1} using determinants.

8. Given the matrix: A = [ 3  1  2 ]

                                      [ 1  1  1 ]

                                      [ 4  2  1 ]

Perform row operations to simplify the matrix and calculate the determinant.

9. A = [ 1  0  0 ]

          [ 0  0  0 ]

          [ 0  0  1 ]

 Find det(A).

10. Find the rank of the matrix by evaluating its minors and determinants.

A = [ 1  2  3 ]

      [ 2  4  6 ]

      [ 1  1  1 ]

11. Given the matrix: A = [ 1  0  0 ]

                                        [ 0  2  3 ]

                                        [ 0  4  5 ]

Perform the column operation C2 -> C2 - 2C1 and calculate the new determinant.

12. A = [ 2  0  0 ]

            [ 0  3  0 ]

            [ 0  0  4 ]

Calculate det(A).

13. For the system of equations:

2x + y = 3 

4x + 2y = 6

Use determinants to find the condition for the system to be consistent.

14. A = [ 1  2  3 ]

            [ 2  4  5 ]

            [ 3  5  6 ]

Calculate det(A).

Significance of Solving Determinants Important Questions

Whether the student is getting ready for board exams or learning mathematics, they need to practice all these key questions on determinants. Let us see why these questions matter to every student.

Foundation for Understanding Advanced Concepts

Determinants have many advanced concepts in mathematics attached to them. Some of such concepts include matrices, vector algebra, linear transformations, and systems of linear equations. Solving determinant problems will prepare the student for more advanced studies in topics such as:

  • Eigenvalues and Eigenvectors
  • Inverse of a Matrix

Improved Problem-Solving and Analytical Skills

There are many ways of solving determinant problems. The two most common include cofactor expansion and row and column operations, which require two different approaches and critical thinking to identify patterns and strategies. This enhances your:

  • Logical Reasoning
  • Attention to Detail

Preparation for Competitive Exams and Future Studies

This study of determinants and matrices is a crucial part of the syllabus for both Class 12 Mathematics as well as several other competitive exams like:

  • JEE (Joint Entrance Examination): This is one of the most important exams in which a proper understanding of determinants is needed. Questions related to this topic often come in both JEE Main and Advance.
  • NEET (National Eligibility cum Entrance Test): Questions related to determinants are not asked much in NEET, like in JEE, but some basic concepts about matrices and determinants are very useful for NEET.
  • University Exams: Most undergraduate courses, ranging from engineering to economics to computer science, include determinants in their curriculum.

Applications in Real-Life Problems

Determinants are not just theoretical concepts. In reality, determinants have very strong applications. Below are some of the most crucial applications of determinants in any field:

  • In economics, determinants are used in modelling the input-output models and for linear programming and analysing market equilibrium conditions.
  • In physics, determinants are used for solving systems of equations that appear in the models of physical systems in both mechanics and quantum physics, for instance, in computing the forces in an object in static equilibrium.

Determinants are one of the key concepts in the Class 12 Mathematics curriculum. When students understand and practice simple concepts that involve the evaluation of determinants, finding inverses of matrices, and their applications to geometric interpretations, they will prepare themselves for exams. With daily practice, students will build confidence and problem-solving ability with these Class 12 Determinants Important questions.

We hope that you practice the above Determinants Class 12 Extra Questions with Solutions and achieve your dream marks.

All the best!

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