Math Problem Statement
Consider the limit \lim_{x\to\infty}\frac{x+\sin x}{x}. Let f(x)=x+\sin x and g(x)=x. Which of the following statements are Turue?
Question 4Answer
a. g'(x)\neq 0 on (M,\infty) for some M>0
b. f,g are differentiable on (M,\infty) for some M>0
c. \lim_{x\to\infty}\frac{f(x)}{g(x)} does not exist
d. f,g are continuous on (M,\infty) for some M>0
e. \lim_{x\to\infty}\frac{f'(x)}{g'(x)} does not exist
f. \lim_{x\to\infty}\frac{f'(x)}{g'(x)} exists
g. \lim_{x\to\infty}\frac{f(x)}{g(x)} is a \frac{\infty}{\infty} form
Solution
Let's evaluate the limit and the given statements carefully.
We are given:
and two functions: and .
Statement a. on for some
- , so .
- Since is non-zero for all , this statement is True.
Statement b. and are differentiable on for some
- is differentiable because both and are differentiable.
- is also differentiable since it's a simple linear function.
- Thus, both functions are differentiable on , so this statement is True.
Statement c. does not exist
Let's compute the limit:
Since as , we get:
This limit exists, so this statement is False.
Statement d. and are continuous on for some
- is continuous because both and are continuous functions.
- is continuous as a linear function.
- Thus, both and are continuous on , making this statement True.
Statement e. does not exist
Let's differentiate and :
Now, we compute:
Since oscillates between and , the expression oscillates between and . Therefore, the limit does not exist because of this oscillation. Thus, this statement is True.
Statement f. exists
From the reasoning above, the limit does not exist due to the oscillating behavior of , so this statement is False.
Statement g. is a form
- When we initially compute the limit, the form is indeed an indeterminate form because both the numerator and denominator go to infinity as .
- Therefore, this statement is True.
Summary of True/False:
- a. True
- b. True
- c. False
- d. True
- e. True
- f. False
- g. True
Would you like more details on any of these steps or explanations?
Here are 5 related questions:
- How do you apply L'Hôpital's Rule to limits involving forms?
- What is the behavior of trigonometric functions like and as ?
- How does the differentiability of functions affect their limits?
- What are the conditions for the existence of limits involving oscillating functions?
- What does the term "indeterminate form" mean in calculus?
Tip: When limits are in indeterminate forms like , consider applying L'Hôpital's Rule to simplify the expression.
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Math Problem Analysis
Mathematical Concepts
Calculus
Limits
Indeterminate Forms
Differentiability
Continuity
Formulas
\lim_{x \to \infty} \frac{x + \sin x}{x} = 1 + \frac{\sin x}{x}
\frac{f'(x)}{g'(x)} = 1 + \cos x
Theorems
L'Hôpital's Rule
Limit Theorem
Suitable Grade Level
Grades 11-12 and early university
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