Question related to inequalities and limits that go to infinity

In summary, if f(x) > g(x) for all x in (-∞, ∞) and limx→∞g(x) = ∞, then limx→∞f(x) = ∞. The theorem that can be used to show this result is the Squeeze Theorem. However, since f(x) is not "squeezed" between two functions, it may not be very helpful. Instead, consider the definition of limx→∞g(x) = ∞, which states that for any real number Y, there exists a real number X such that g(x) > Y for all x > X. Using this fact and the given inequality f(x) > g(x
  • #1
eggmanneo
1
0
I want to show that if [itex] f(x) > g(x) [/itex] [itex] \forall x \in (-\infty, \infty) [/itex] and [itex] \displaystyle\lim_{x\to\infty}g(x)=\infty [/itex], then [itex] \displaystyle \lim_{x\to\infty}f(x)=\infty [/itex]. This result is true, correct? If so, what theorem should I use or reference to show this result? I wasn't sure if the squeeze theorem was application to this problem.
 
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  • #2
Have you considered the Squeeze Theorem?
 
  • #3
I may be entirely incorrect, but I don't think the squeeze theorem would be very helpful. f(x) isn't "squeezed" between two functions.
 
  • #4
Consider what it means for ##\lim_{x \rightarrow \infty} g(x) = \infty## to be true. Given any ##Y \in \mathbb{R}##, there is some ##X \in \mathbb{R}## such that ##g(x) > Y## for all ##x > X##. Now apply the fact that ##f(x) > g(x)##.
 

1. What is the definition of an inequality?

An inequality is a mathematical statement that compares two quantities by using symbols such as <, >, ≤, and ≥. It indicates that one quantity is greater than or less than the other.

2. How do you solve an inequality?

To solve an inequality, you need to isolate the variable on one side of the inequality sign and simplify the other side. Remember to reverse the inequality sign if you multiply or divide by a negative number.

3. What is the difference between strict and non-strict inequalities?

A strict inequality, denoted by < or >, indicates that the two quantities being compared are not equal to each other. A non-strict inequality, denoted by ≤ or ≥, includes the possibility that the quantities are equal to each other.

4. What is a limit that goes to infinity?

A limit that goes to infinity is a mathematical concept that describes the behavior of a function as the input value gets infinitely large. In other words, the function's output approaches a certain value as the input gets increasingly larger.

5. How do you evaluate a limit that goes to infinity?

To evaluate a limit that goes to infinity, you can use the properties of limits, such as the limit of a sum, difference, or product. You can also use L'Hopital's rule, which states that the limit of a quotient can be evaluated by taking the derivative of the numerator and denominator separately.

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