Question

In: Advanced Math

a) Let S ⊂ R, assuming that f : S → R is a continuous function,...

a) Let S ⊂ R, assuming that f : S → R is a continuous function, if the
image set {f(x); x ∈ S} is unbounded prove that S is unbounded.


b) Let f : [0, 100] → R be a continuous function such that f(0) = f(2),
f(98) = f(100) and the function g(x) := f(x+ 1)−f(x) is equal to zero in at most
two points of the interval [0, 100].

Prove that (f(50) − f(49))(f(25) − f(24)) > 0.

Solutions

Expert Solution


Related Solutions

Let f : R → R be a function. (a) Prove that f is continuous on...
Let f : R → R be a function. (a) Prove that f is continuous on R if and only if, for every open set U ⊆ R, the preimage f −1 (U) = {x ∈ R : f(x) ∈ U} is open. (b) Use part (a) to prove that if f is continuous on R, its zero set Z(f) = {x ∈ R : f(x) = 0} is closed.
Let A ⊆ R, let f : A → R be a function, and let c...
Let A ⊆ R, let f : A → R be a function, and let c be a limit point of A. Suppose that a student copied down the following definition of the limit of f at c: “we say that limx→c f(x) = L provided that, for all ε > 0, there exists a δ ≥ 0 such that if 0 < |x − c| < δ and x ∈ A, then |f(x) − L| < ε”. What was...
Let φ : R −→ R be a continuous function and X a subset of R...
Let φ : R −→ R be a continuous function and X a subset of R with closure X' such that φ(x) = 1 for any x ∈ X. Prove that φ(x) = 1 for all x ∈ X.'  
Suppose a function f : R → R is continuous with f(0) = 1. Show that...
Suppose a function f : R → R is continuous with f(0) = 1. Show that if there is a positive number x0 for which f(x0) = 0, then there is a smallest positive number p for which f(p) = 0. (Hint: Consider the set {x | x > 0, f(x) = 0}.)
Let f be a continuous function on [a, b] which is differentiable on (a,b). Then f...
Let f be a continuous function on [a, b] which is differentiable on (a,b). Then f is non-decreasing on [a,b] if and only if f′(x) ≥ 0 for all x ∈ (a,b), while if f is non-increasing on [a,b] if and only if f′(x) ≤ 0 for all x ∈ (a, b). can you please prove this theorem? thank you!
6. (a) let f : R → R be a function defined by f(x) = x...
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)...
a) State the definition that a function f(x) is continuous at x = a. b) Let...
a) State the definition that a function f(x) is continuous at x = a. b) Let f(x) = ax^2 + b if 0 < x ≤ 2 18/x+1 if x > 2 If f(1) = 3, determine the values of a and b for which f(x) is continuous for all x > 0.
Rolle's Theorem, "Let f be a continuous function on [a,b] that is differentiable on (a,b) and...
Rolle's Theorem, "Let f be a continuous function on [a,b] that is differentiable on (a,b) and such that f(a)=f(b). Then there exists at least one point c on (a,b) such that f'(c)=0." Rolle's Theorem requires three conditions be satisified. (a) What are these three conditions? (b) Find three functions that satisfy exactly two of these three conditions, but for which the conclusion of Rolle's theorem does not follow, i.e., there is no point c in (a,b) such that f'(c)=0. Each...
6.3.8. Problem. Let f : A → B be a continuous bijection between subsets of R....
6.3.8. Problem. Let f : A → B be a continuous bijection between subsets of R. (a) Show by example that f need not be a homeomorphism. (b) Show that if A is compact, then f must be a homeomorphism. 6.3.9. Problem. Find in Q a set which is both relatively closed and bounded but which is not compact.
Let f : R → S and g : S → T be ring homomorphisms. (a)...
Let f : R → S and g : S → T be ring homomorphisms. (a) Prove that g ◦ f : R → T is also a ring homomorphism. (b) If f and g are isomorphisms, prove that g ◦ f is also an isomorphism.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT