Question 1
What is the best linear approximation of around

The IIT Madras BS Machine Learning Foundations (MLF) Quiz 1 paper sat on 19 Jul 2026, in the May 2026 term: 14 questions for 41 marks in 120 minutes. Every question is below with its answer. Take it as a timed mock test to be marked, or read it through first.
What is the best linear approximation of around




Correct answer

A company manufactures a special rectangular metal sheet. The production cost (in hundreds of rupees) depends on its length meters and width meters according to . At a particular stage, the dimensions of the sheet are . The company plans to change the dimensions in the direction represented by the vector
and wants to determine how rapidly the production cost changes in that specific direction. Find the directional derivative of at the point in the direction of .
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Correct answer

Find the projection matrix that projects the plane onto the line .




Correct answer

Let be a real symmetric matrix. Consider the following statements. (1) is orthogonally diagonalizable. (2) is not diagonalizable. (3) All the eigenvalues of are real. (4) The eigenvalues of may be imaginary. (5) Eigenvectors corresponding to distinct eigenvalues of are linearly independent. (6) Eigenvectors corresponding to distinct eigenvalues of are linearly dependent. Which of the above statements are true?
(1), (3), (5)
(2), (4), (6)
(2), (3), (5)
(1), (4), (6)
Correct answer
(1), (3), (5)
Let and be two square matrices of order . The rows of are represented by row vectors , from top to bottom, and the columns of are represented by column vectors , from left to right. The second row of is . Which of the following is/are true?
The second row of is .
The second column of is .
The row space of is contained in the row space of .
The row space of is contained in the row space of .
Correct answers
The second row of is .
The row space of is contained in the row space of .
is a square matrix of order with the eigenvalue repeated twice. Which of the following is/are true?
is invertible.
Each of the entries on the main diagonal of is equal to .
has two linearly independent eigenvectors.
is not invertible, where is the identity matrix.
Correct answers
is invertible.
is not invertible, where is the identity matrix.
Suppose is a matrix with rank 4. Which of the following is/are true?
Columns of are linearly independent.
Null space of contains only the zero vector.
Row space of is .
Left null space of has dimension 2.
Correct answers
Columns of are linearly independent.
Null space of contains only the zero vector.
Left null space of has dimension 2.
Which of the following represents the set of all points on the line passing through along the direction ? (More than one option can be correct).
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Correct answers
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Let be two vectors with and . Find the maximum possible value of , where represents the absolute value of . Your answer should be an integer.
A written answer, not marked automatically.
Let
be the matrix whose eigenvalues are and , and whose eigenvectors are and respectively. Find . Your answer should be an integer.
A written answer, not marked automatically.
Consider the following dataset consisting of two features and :
We want to reduce the dimensionality of the dataset from to using the following encoder- decoder pairs.
The reconstruction loss is defined as the mean squared distance between the reconstructed input and the original input. Based on the above information, answer the given sub-questions.
Compute the reconstruction loss for Pair 1. NOTE: Your answer should be an integer
A written answer, not marked automatically.
Consider the following dataset consisting of two features and :
We want to reduce the dimensionality of the dataset from to using the following encoder- decoder pairs.
The reconstruction loss is defined as the mean squared distance between the reconstructed input and the original input. Based on the above information, answer the given sub-questions.
Compute the reconstruction loss for Pair 2. NOTE: Your answer should be an integer
A written answer, not marked automatically.
Consider the following dataset consisting of two features and :
We want to reduce the dimensionality of the dataset from to using the following encoder- decoder pairs.
The reconstruction loss is defined as the mean squared distance between the reconstructed input and the original input. Based on the above information, answer the given sub-questions.
Which encoder-decoder pair performs better?
Pair-1
Pair-2
Correct answer
Pair-1
Consider the following dataset consisting of two features and :
We want to reduce the dimensionality of the dataset from to using the following encoder- decoder pairs.
The reconstruction loss is defined as the mean squared distance between the reconstructed input and the original input. Based on the above information, answer the given sub-questions.
A written answer, not marked automatically.