Category Archives: linear algebra

Linear Algebra and Its Applications, Exercise 3.3.13

Exercise 3.3.13. Using least squares, find the line that is the best fit to the following measurements: at at at at Also, given the matrix find the projection of onto the column space . Answer: Assuming that the line in … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.12

Exercise 3.3.12. Given the subspace spanned by the two vectors and find the following: a) a set of basis vectors for b) the matrix that projects onto c) the vector in that has the minimum distance to the vector in Answer: … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.11

Exercise 3.3.11. Suppose that is a subspace with orthogonal complement , with  a projection matrix onto and a projection matrix onto . What are and ? Also, show that is its own inverse. Answer: Given any vector we have where … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.10

Exercise 3.3.10. Given mutually orthogonal vectors , , and and the matrix with columns  and , what are and ? What is the projection of onto the plane formed by and ? Answer: We have where the zero entries are the result … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.9

Exercise 3.3.9. Suppose that is a matrix such that . a) Show that is a projection matrix. b) If then what is the subspace onto which projects? Answer: a) To show that is a projection matrix we must show that and also … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.8

Exercise 3.3.8. Suppose that is a projection matrix from onto a subspace with dimension . What is the column space of ? What is its rank? Answer: Suppose that is a arbitrary vector in . From the definition of we know … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.7

Exercise 3.3.7. Given the two vectors and find the projection matrix that projects onto the subspace spanned by and . Answer: The subspace spanned by  and is the column space where The projection matrix onto the subspace is then . We … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.6

Exercise 3.3.6. Given the matrix and vector defined as follows find the projection of onto the column space of . Decompose the vector into the sum of two orthogonal vectors and where is in the column space. Which subspace is in? … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.5

Exercise 3.3.5. Given the system with no solution, provide a graph of a straight line that minimizes and solve for the equation of the line. What is the result of projecting the vector onto the column space of ? Answer: … Continue reading

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Linear Algebra and Its Applications, Exercise 3.3.4

Exercise 3.3.4. Given expand the expression , compute its partial derivatives with respect to and , and set them to zero. Compare the resulting equations to to confirm that you obtain the same normal equations in both cases (i.e., using … Continue reading

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