68 practice questions on Matrices , sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Matrices notes .
Matrix A (3 rows x 3 columns) a11 a12 a13 a21 a22 a23 a31 a32 a33 column 1 column 2 column 3 row 1 row 2 row 3 Element aij of matrix A sits at the intersection of row i and column j.
Easy - 20 questions Q1.
A matrix with equal number of rows and columns is called a:
A Row matrixB Column matrixC Square matrixD Rectangular matrixShow answer & explanation →
Q4.
A square matrix in which all elements except the main diagonal are zero is called a:
A Identity matrixB Zero matrixC Symmetric matrixD Diagonal matrixShow answer & explanation →
Q7.
The transpose of a matrix A is obtained by:
A Multiplying every element by -1B Interchanging rows and columnsC Adding A to itselfD Squaring every elementShow answer & explanation →
Q8.
A matrix in which all elements are zero is called a:
A Unit matrixB Zero matrixC Diagonal matrixD Scalar matrixShow answer & explanation →
Q9.
Two matrices can be added only if they have:
A The same determinant value calculated for bothB The same number of rows, even with differing columnsC The same number of columns, even with differing rowsD The same order (same rows and columns)Show answer & explanation →
Q13.
A square matrix A is called singular if:
A det(A) = 1B det(A) = 0C A = A<sup>T</sup>D A has all positive elementsShow answer & explanation →
Q15.
A skew-symmetric matrix satisfies:
A A = A<sup>T</sup>B A = -A<sup>T</sup>C det(A) = 1D A = 2A<sup>T</sup>Show answer & explanation →
Q20.
The matrix [[1,0,0],[0,2,0],[0,0,3]] is an example of a:
A Identity matrixB Scalar matrixC Null matrixD Diagonal matrixShow answer & explanation →
Medium - 20 questions Q24.
For the product AB to be defined, the number of columns of A must equal the number of ___ of B:
A rowsB columnsC elementsD diagonalsShow answer & explanation →
Q28.
The identity matrix has 1s along the ___ and 0s elsewhere:
A main diagonalB first rowC last columnD four cornersShow answer & explanation →
Q29.
The transpose of a matrix is obtained by interchanging its:
A rows and columnsB plus and minus signsC two diagonalsD elements at randomShow answer & explanation →
Q34.
Matrix multiplication is, in general:
A not commutativeB fully commutativeC always undefinedD always exactly zeroShow answer & explanation →
Q37.
Because A + B = B + A for matrices, matrix addition is:
A commutativeB non-associativeC distributive onlyD undefinedShow answer & explanation →
Q40.
The additive identity for matrices of a given order is the:
A null matrixB identity matrixC scalar matrixD transpose matrixShow answer & explanation →
Hard - 28 questions Q42.
The Vandermonde determinant for distinct values (a, b, c) equals:
A (b-a)(c-a)(c-b)B a<sup>2</sup>+b<sup>2</sup>+c<sup>2</sup>-ab-bc-caC (a+b+c)<sup>3</sup>D abc(a+b+c)Show answer & explanation →
Q43.
The null space (kernel) of matrix A consists of all vectors x such that:
A Ax = xB Ax = 0C A<sup>T</sup> x = 0D Ax = b for some bShow answer & explanation →
Q45.
For a Hermitian matrix H, the defining property is:
A H = H<sup>T</sup>B H = -H (conjugate transpose)C H = H* (conjugate)D H = H<sup>dagger</sup> (conjugate transpose)Show answer & explanation →
Q47.
Schur decomposition states that every square matrix A can be written as A = QTQ<sup>-1</sup> where:
A T is diagonalB T is lower triangular and Q is orthogonalC T is upper triangular and Q is unitaryD Q = IShow answer & explanation →
Q49.
The inverse of a matrix A is given by A⁻¹ = (adj A) divided by:
A the value |A|B the matrix AC the transpose AᵀD the number 1Show answer & explanation →
Q55.
The trace of a square matrix is the sum of its:
A its diagonal elementsB all of its elementsC just its first rowD all its determinantsShow answer & explanation →
Q56.
If A and B are both symmetric matrices of the same order, then A + B is:
A symmetricB skew-symmetricC nullD identityShow answer & explanation →
Q57.
Every square matrix can be written uniquely as the sum of a symmetric matrix and a:
A a skew-symmetric oneB a diagonal matrixC a scalar matrixD a null matrixShow answer & explanation →
Q58.
A square matrix A for which Aᵏ = 0 for some positive integer k is called:
A nilpotentB idempotentC orthogonalD symmetricShow answer & explanation →
Q59.
The product of a square matrix and its inverse is the:
A identity matrixB null matrixC original matrixD transpose matrixShow answer & explanation →
Q62.
A matrix that is both symmetric and skew-symmetric must be:
A the identity matrixB the null matrixC a diagonal matrixD a scalar matrixShow answer & explanation →
Q65.
The inverse of the matrix [[2, 3], [1, 2]] is:
A [[2, −3], [−1, 2]]B [[2, 3], [1, 2]]C [[−2, 3], [1, −2]]D [[2, −1], [−3, 2]]Show answer & explanation →