Let (X,d) be a metric space. The graph of f : X → R is the...
Let (X,d) be a metric space. The graph of f : X → R is the set
{(x, y) E X X Rly = f(x)}. If X is connected and f is continuous,
prove that the graph of f is also connected.
(a) Let <X, d> be a metric space and E ⊆ X. Show
that E is connected iff for all p, q ∈ E, there is a connected A ⊆
E with p, q ∈ E.
b) Prove that every line segment between two points in R^k
is connected, that is Ep,q = {tp + (1 − t)q |
t ∈ [0, 1]} for any p not equal to q in R^k.
C). Prove that every convex subset of R^k...
(Connected Spaces)
(a) Let <X, d> be a metric space and E ⊆ X. Show that E is
connected iff for all p, q ∈ E, there is a connected A ⊆ E with p,
q ∈ E.
b) Prove that every line segment between two points in R^k
is connected, that is Ep,q = {tp + (1 − t)q |
t ∈ [0, 1]} for any p not equal to q in R^k.
C). Prove that every convex subset...
Answer for a and be should be answered independently.
Let (X,d) be a metric space, and
a) let A ⊆ X. Let U be the set of isolated points of A. Prove
that U is relatively open in A.
b) let U and V be subsets of X. Prove that if U is both open and
closed, and V is both open and closed, then U ∩ V is also both open
and closed.
Q2. Let (E, d) be a metric space, and let x ∈ E. We say that x
is isolated if the set {x} is open in E.
(a) Suppose that there exists r > 0 such that Br(x) contains
only finitely many points. Prove that x is isolated.
(b) Let E be any set, and define a metric d on E by setting d(x,
y) = 0 if x = y, and d(x, y) = 1 if x and y...
1(i) Show, if (X, d) is a metric space, then d∗ : X × X → [0,∞)
defined by d∗(x, y) = d(x, y) /1 + d(x, y) is a metric on X. Feel
free to use the fact: if a, b are nonnegative real numbers and a ≤
b, then a/1+a ≤ b/1+b .
1(ii) Suppose A ⊂ B ⊂ R. Show, if A is not empty and B is
bounded below, then both inf(A) and inf(B) exist and...
Let X be a metric space and t: X to X be a map that preserves
distances: d(t(x), t(y)) = d(x, y). Give an example in whicht is
not bijective.
Could let t: x to x+1,x non-negative, but how does this mean t
is not surjective?
Any help will be much appreciated!
Let
f(x) = 14 −
2x.
(a)
Sketch the region R under the graph of f on
the interval
[0, 7].
The x y-coordinate plane is given. There is 1
line and a shaded region on the graph.
The line enters the window at y = 13 on the positive
y-axis, goes down and right, and exits the window at
x = 6.5 on the positive x-axis.
The region is below the line.
The x y-coordinate plane is given. There...
Let X be a compact space and let Y be a Hausdorff space. Let f ∶
X → Y be continuous. Show that the image of any closed set in X
under f must also be closed in Y .
6. (a) let f : R → R be a function defined by
f(x) =
x + 4 if x ≤ 1
ax + b if 1 < x ≤ 3
3x x 8 if x > 3
Find the values of a and b that makes f(x) continuous on R. [10
marks]
(b) Find the derivative of f(x) = tann 1
1 ∞x
1 + x
. [15 marks]
(c) Find f
0
(x) using logarithmic differentiation, where f(x)...