Problem 5 (a) Let A be an n × m matrix, and suppose that there exists a m × n matrix B such that BA = 1- (i) Let b є Rn be such that the system of equations Ax b has at least one solution. Prove that...
Problem 5. A subset A c Rn is an affine subspace of Rn if there exists a vector b є R', and a underlying vector subspace W of Rn such that (a) Describe all the affine subspaces of R2 which are not vector subspaces of R2. (b) Consider A є Rnxn, b є Rn and the system of linear equations Ax-b Prove that (i) if Ar= b is consistent, then its solution set is an affine subspace of Rn with...
Problem 5. A subset A C R', is an afǐпє subspace of Rn if there exists a vector b underlying vector subspace W of R" such that Rn and an (a) Describe all the affine subspaces of IR2 which are not vector subspaces of R2 (b) Consider A e R"Xn, beR" and the system of linear equations Ar- b. Prove that: (i) if A-b is consistent, then its solution set is an affine subspace of R" with underlying (ii) if...
Let A be an m × n matrix, let x Rn and let 0 be the zero vector in Rm. (a) Let u, v є Rn be any two solutions of Ax 0, and let c E R. Use the properties of matrix-vector multiplication to show that u+v and cu are also solutions of Ax O. (b) Extend the result of (a) to show that the linear combination cu + dv is a solution of Ax 0 for any c,d...
2. Suppose that A is an rn x n matrix and b є С". Prove that the linear system CSA, b) is consistent if and only if r(A) = r(Ab) 2. Suppose that A is an rn x n matrix and b є С". Prove that the linear system CSA, b) is consistent if and only if r(A) = r(Ab)
Problem 5. A subset A C R is an affine subspace of R" if there exists a vector bE R" and an underlying vector subspace W of R" such that (a) Describe all the affine subspaces of R2 which are not vector subspaces of R2 (b) Consider A E Rnx, bER" and the system of linear equations AT . Prove that: (i) if Ais consistent, then its solution set is an affine subspace of R" with underlying (ii) if At...
Problem 1. Let A be an m x m matrix. (a) Prove by induction that if A is invertible, then for every n N, An is invertible. (b) Prove that if there exists n N such that An is invertible, then A is invertible. (c) Let Ai, . . . , An be m x m matrices. Prove that if the product Ai … An is an invertible matrix, then Ak is invertible for each 1 < k< n. (d)...
12.3 Least angle property of least squares. Suppose the m × n matrix A has linearly independent columns, and b is an m-vector. Let x ATb denote the least squares approximate solution (a) Show that for any n-vector a, (Ax)Tb - (Aa)"(Aâ), i.e., the inner product of Ax and b is the same as the inner product of Ax and Ai. Hint. Use (Ax)b (ATb) and (ATA)2 = ATb (b) Show that when A and b are both nonzero, we...
13. Determine whether the following assertion is true: let A be a 5x3 matrix. If Ax 0 has a single solution, then for every b the system Ax- b has a single solution 14. Determine whether the following assertion is true: let A be an n×n matrix, and x an nxl vector. The system AT-0 has a nontrivial solution if and only if the system Ax 0 has a nontrivial solution 13. Determine whether the following assertion is true: let...
Let A e Rmxn. The linear system Ax = b can have either: (i) a unique solution, (ii) no solution, or (iii) infinitely many solutions. If A is square and invertible, there is a unique solution, which can be written as x = A-'b. The concept of pseudoinverse seeks to generalise this idea to non-square matrices and to cases (ii) and (iii). Taking case (ii) of an inconsistent linear system, we may solve the normal equations AT Ar = Ab...
Problem 8 Suppose that the matrix equation Ax = b represents a consistent system of m equations in n unknowns and Xo is a specific solution of this system. Show that any solution of this system E can be written in the form x = xo + x1, where x1 is a solution of Ax = 0.