Chapter 3: Problem 33
Show that a matrix \(B\) has a left inverse if and only if \(B^{T}\) has a right inverse.
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Chapter 3: Problem 33
Show that a matrix \(B\) has a left inverse if and only if \(B^{T}\) has a right inverse.
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Let \(\mathrm{x}\) and \(\mathrm{y}\) be nonzero vectors in \(\mathbb{R}^{m}\) and \(\mathbb{R}^{n},\) respectively, and let \(A=\mathbf{x y}^{T}\) (a) Show that \(\\{x\\}\) is a basis for the column space of \(A\) and that \(\left\\{\mathbf{y}^{T}\right\\}\) is a basis for the row space of \(A\). (b) What is the dimension of \(N(A) ?\)
Let \(A \in \mathbb{R}^{m \times n}, B \in \mathbb{R}^{n \times r},\) and \(C=A B .\) Show that (a) if \(A\) and \(B\) both have linearly independent column vectors, then the column vectors of \(C\) will also be linearly independent. (b) if \(A\) and \(B\) both have linearly independent row vectors, then the row vectors of \(C\) will also be linearly independent. [Hint: Apply part (a) to \(C^{T}\).]
We can define a one-to-one correspondence between the elements of \(P_{n}\) and \(\mathbb{R}^{n}\) by $$\begin{array}{l} p(x)=a_{1}+a_{2} x+\cdots+a_{n} x^{n-1} \\ \leftrightarrow\left(a_{1}, \ldots, a_{n}\right)^{T}=\mathbf{a} \end{array}$$ Show that if \(p \leftrightarrow \mathbf{a}\) and \(q \leftrightarrow \mathbf{b},\) then (a) \(\alpha p \leftrightarrow \alpha\) a for any scalar \(\alpha\) (b) \(p+q \leftrightarrow \mathbf{a}+\mathbf{b}\) [In general, two vector spaces are said to be isomorphic if their elements can be put into a one-to-one correspondence that is preserved under scalar multiplication and addition as in (a) and (b).]
Let \(\mathbf{u}_{1}=(1,1,1)^{T}, \mathbf{u}_{2}=(1,2,2)^{T}\) \(\mathbf{u}_{3}=(2,3,4)^{T}\) (a) Find the transition matrix corresponding to the change of basis from \(\left\\{\mathbf{e}_{1}, \mathbf{e}_{2}, \mathbf{e}_{3}\right\\}\) to \(\left\\{\mathbf{u}_{1}, \mathbf{u}_{2}, \mathbf{u}_{3}\right\\}\) (b) Find the coordinates of each of the following vectors with respect to \(\left\\{\mathbf{u}_{1}, \mathbf{u}_{2}, \mathbf{u}_{3}\right\\}\) (i) \((3,2,5)^{T}\) (ii) \(\quad(1,1,2)^{T}\) (iii) \((2,3,2)^{T}\)
Let \(S\) be the subspace of \(P_{3}\) consisting of all polynomials \(p(x)\) such that \(p(0)=0,\) and let \(T\) be the subspace of all polynomials \(q(x)\) such that \(q(1)=\) 0\. Find bases for (a) \(S\) (b) \(T\) (c) \(S \cap T\)
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