2) Let v, w, and x be vectors in Rn.
a) If v is the zero vector, what geometric object represents all
linear
combinations of v?
b) Same question as a), except now for a nonzero v.
c) Same question as a) except now for nonzero vectors v and w (be
care-
ful!).
d) Same question as a) except now for nonzero vectors v, w, and x
(be
extra careful!).
Let W be a subspace of Rn with an orthogonal basis {w1, w2,
..., wp} and let {v1,v2,...,vq} be an orthogonal basis for W⊥.
Let
S = {w1, w2, ..., wp, v1, v2, ..., vq}.
(a) Explain why S is an orthogonal set. (b) Explain why S
spans Rn.
(c) Showthatdim(W)+dim(W⊥)=n.
1.
a. Show that for any y ∈ Rn, show that yyT
is positive semidefinite.
b. Let X be a random vector in Rn with covariance
matrix Σ = E[(X − E[X])(X − E[X])T]. Show that Σ is
positive semidefinite.
2. Let X and Y be real independent random variables with PDFs
given by f and g, respectively. Let h be the PDF of the random
variable Z = X + Y .
a. Derive a general expression for h...
Let V = { S, A, B, a, b, λ} and T = { a, b }, Find the
languages generated by the grammar G = ( V, T, S, P } when the set
of productions consists of:
S → AB, A → aba, B → bab.
S → AB, S → bA, A → bb, B → aa.
S → AB, S → AA, A → Ab, A → a, B → b.
S → A, S →...
Let T: V →W be a linear transformation from V to W.
a) show that if T is injective and S is a linearly independent
set of vectors in V, then T(S) is linearly independent.
b) Show that if T is surjective and S spans V,then T(S) spans
W.
Please do clear handwriting!
Let f : Rn → R be a differentiable function. Suppose that a
point x∗ is a local minimum of f along every line passes through
x∗; that is, the function
g(α) = f(x^∗ + αd)
is minimized at α = 0 for all d ∈ R^n.
(i) Show that ∇f(x∗) = 0.
(ii) Show by example that x^∗ neen not be a local minimum of f.
Hint: Consider the function of two variables
f(y, z) = (z − py^2)(z...
Let V and W be Banach spaces and suppose T : V → W is a linear
map. Suppose that for every f ∈ W∗ the corresponding linear map f ◦
T on V is in V ∗ . Prove that T is bounded.
Let a < c < b, and let f be defined on [a,b]. Show that f
∈ R[a,b] if and only if f ∈ R[a, c] and f ∈ R[c, b]. Moreover,
Integral a,b f = integral a,c f + integral c,b f .