Problem 6.7. Let A be any nx k matrix (1) Prove that the k x k matrix ATA and the matrix A have the same nullspace. Use this to prove that rank(ATA) = rank(A). Similarly, prove that the n x n matrix AAT and the matrix AT have the same nullspace, and conclude that rank(AAT) =rank(AT) We will prove later that rank(AT) = rank(A) (2) Let a1,.. ., a be k linearly independent vectors in R" (1 k

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question

Please, help me with a step by step solutions to this problem and I will be very grateful to you. I don't have a strong background in algebra. I hope you will help.

Problem 6.7. Let A be any nx k matrix
(1) Prove that the k x k matrix ATA and the matrix A have the same nullspace. Use
this to prove that rank(ATA) = rank(A). Similarly, prove that the n x n matrix AAT and
the matrix AT have the same
nullspace, and conclude that rank(AAT) =rank(AT)
We will prove later that rank(AT) = rank(A)
(2) Let a1,.. ., a be k linearly independent vectors in R" (1 k <n), and let A be the
n x k matrix whose ith column is aj. Prove that A A has rank k, and that it is invertible
Let P A(ATA)-1AT
an n x n matrix). Prove that
What is the matrix P when k
1?
(3) Prove that the image of P is the subspace V spanned by a1,.. . ,ak, or
the set of all vectors in R" of the form Ar, with r E R*. Prove that the nullspace U of P is
the set of vectors uE R" such that A u 0. Can you give a geometric interpretation of U?
equivalently
projection of R" onto the subspace V spanned by ai,... , ak, and
Conclude that P is a
that
R" U V
Transcribed Image Text:Problem 6.7. Let A be any nx k matrix (1) Prove that the k x k matrix ATA and the matrix A have the same nullspace. Use this to prove that rank(ATA) = rank(A). Similarly, prove that the n x n matrix AAT and the matrix AT have the same nullspace, and conclude that rank(AAT) =rank(AT) We will prove later that rank(AT) = rank(A) (2) Let a1,.. ., a be k linearly independent vectors in R" (1 k <n), and let A be the n x k matrix whose ith column is aj. Prove that A A has rank k, and that it is invertible Let P A(ATA)-1AT an n x n matrix). Prove that What is the matrix P when k 1? (3) Prove that the image of P is the subspace V spanned by a1,.. . ,ak, or the set of all vectors in R" of the form Ar, with r E R*. Prove that the nullspace U of P is the set of vectors uE R" such that A u 0. Can you give a geometric interpretation of U? equivalently projection of R" onto the subspace V spanned by ai,... , ak, and Conclude that P is a that R" U V
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 8 steps with 8 images

Blurred answer
Knowledge Booster
Factorization
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, advanced-math and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,