Matrix Algebra Gate Questions | Engineering Mathematics

Question 1
The number of distinct eigenvalues of the matrix is equal to __________.
A
Fill in the Blank Type Question
Question 1 Explanation: 
Question 2
Consider the 5 × 5 matrix It is given that A has only one real Eigen value. Then the real Eigen value of A is
A
-2.5
B
0
C
15
D
25
Question 2 Explanation: 
If sum of all the rows or columns are same, then that
sum = one eigen value of that matrix


Sum of all rows
(15-x) * |Matrix| = 0
15 is a factor .


Another Approach
Question 3
The rank of the matrix M = is
A
0
B
1
C
2
D
3
Question 3 Explanation: 
|M |=
= 5(0-12) – 10(6-6) +10(6-0)= -60-0+60=0
But a 2×2 minor, =0-10=-10≠0
Rank = 2
Question 4

Consider the following statement about the linear dependence of the real valued functions y1= 1, y2= x and y 3 =x2, over the field of real numbers.
I. y1, y2 and y3 are linearly independent on -1 x 0
II. y1 , y2 and y3 are linearly dependent on 0 x 1
III. y1 , y2 and y3 are linearly independent on 0 x 1
IV. y1, y2 and y3 are linearly dependent on -1 x 0
Which one among the following is correct?

A
Which one among the following is correct?
B
Both I and III are true
C
Both II and IV are true
D
Both III and IV are true
Question 4 Explanation: 
Given
y1= 1, y 2= x, y 3= x2
Consider

= =2 ≠0

y1, y2, y3 are linearly independent x
Question 5
Consider matrix and vector The number of distinct real values of for which the equation has infinitely many solution is ___________.
A
Fill in the Blank Type Question
Question 5 Explanation: 
Question 6
Let M4 = I, (where I denotes the identity matrix) and M ≠ I, M2 ≠I and M3 ≠I. Then, for any natural number k, M-1  equals:
A
M4k+1
B
M4k + 2
C
M4k+3
D
M4k
Question 6 Explanation: 
Question 7
The matrix has det A. = 100 and trace A=14
The value of is
A
Fill in the Blank Type Question
Question 7 Explanation: 
Question 8
Consider a square matrix Where x is unknown. If the eigenvalues of the matrix A are and the x is equal to
A
B
C
D
Question 8 Explanation: 
Given
Product of eigen values = Det of A
Question 9
For A = Deg, the determinant of AT A–1 is
A
sec2 x
B
cos 4x
C
1
D
0
Question 9 Explanation: 
Question 10
For matrices of same dimension M, N and scalar c, which one of these properties DOES NOT ALWAYS hold?
A
B
(cM)T = c(M)T
C
D
Question 10 Explanation: 
Matrix multiplication is not commutative in general.
All other are properties of matrix.

Refer: www.khanacademy.org
Question 11
A real (4 × 4) matrix A satisfies the equation A2 = I, where I is the (4 × 4) identity matrix. The positive eigen value of A is __________.
A
1
B
2
C
4
D
8
Question 11 Explanation: 
Question 12
Consider the matrix:

Which is obtained by reversing the order of the columns of the identity matrix I6.
Let P= I6 + αJ6 where α is a non-negative real number.
The value of α for which det(P) = 0 is ___________.
A
0
B
1
C
2
D
4
Question 12 Explanation: 



Since, α is non-negative real number. Hence,
α = 1
Question 13
The determinant of matrix A is 5 and the determinant of matrix B is 40. The determinant of matrix AB is ________.
A
100
B
8
C
1000
D
200
Question 13 Explanation: 
Determinant of matrix AB will be
Determinant of (A) * Determinant of (B)
5*40 = 200
so answer = 200
Question 14
The system of linear equations
A
a unique solution
B
infinitely many solutions
C
no solution
D
exactly two solutions
Question 14 Explanation: 


Clearly rank(A)=2 , rank(A/B) = 2 , number of unknowns = 3
so rank (A) = rank (A / B) =2
Since, rank (A) = rank (A / B) < number of unknowns
Equations have infinitely many solutions.
Question 15
The maximum value of the determinant among all 2×2 real symmetric matrices with trace 14 is ________.
A
40
B
45
C
49
D
52
Question 15 Explanation: 
Question 16
Which one of the following statements is NOT true for a square matrix?
A
If A is upper triangular, the eigenvalues of A are the diagonal elements of it
B
If A is real symmetric, the eigenvalues of A are always real and positive
C
If A is real, the eigenvalues of A and AT are always the same
D
If all the principal minors of A are positive, all the eigenvalues of A are also positive
Question 16 Explanation: 
Question 17
Let A be an m × n matric and B an n × m matric. It is given that determinant determinant where is the k × k identity matrix. Using the above property, the determinant of the matrix given below is
A
2
B
5
C
8
D
16
Question 17 Explanation: 
Question 18
Given that and , the value of A3 is
A
15 A + 12 I
B
19A + 30 I
C
17A + 15 I
D
17 A + 21I
Question 18 Explanation: 
Characteristic equation of A is


(-5-λ)(-λ) + 6 = 0

So,
(by Cayley Hamilton theorem)
A2 = –5A – 6I
Multiplying by A on both sides, we have,
A3 =-5A2-6A
A3 = -5(-5A-6I)-6A
= 19A + 30I
There are 18 questions to complete.

This Post Has 8 Comments

  1. Anonymous

    I cant solve the questioner! because its so hard!

    1. Karthik

      First you need to try….nothing is impossible when you want fulfil your dream .. All d best

  2. Anonymous

    right answer of Question no. 9 is 1

    1. Anonymous

      no, its correct

  3. 758542

    Yes

  4. Gate aspirant

    Answer for question no 9 is option C that is 1. A inverse can be written an 1/A and A transpose is same as A ….so A*(1/A) gets cancelled and the answer is 1.

  5. Gate aspirant

    Answer for question no 9 is option C that is 1. A inverse can be written an 1/A and A transpose is same as A ….so A*(1/A) gets cancelled and the answer is 1.

  6. Gatee

    A transpose is not same as matrix A

Leave a Reply