Calculating Limit: How to Show Lim x^2-sin(x)→∞

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In summary, using the Squeeze Theorem, it can be shown that lim x^2 - sin(x) as x tends to infinity is infinity. This is because x^2 - 1 and x^2 + 1 both tend to infinity as x grows large without bound, and since x^2 - sin(x) is always between these two functions, it must also tend to infinity.
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gipc
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How do I formally show that lim x^2 - sin(x) as x tends to infinity is infinity?
 
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I suppose you could look at the minimum possible value of your function... since sin(x) can never be greater than one, your equation can never be less than x^2-1. So work with that instead.
 
  • #3
There's a theorem that is sometimes called the Squeeze Theorem or Squeeze Play Theorem. If f(x) <= g(x) <= h(x) for all x in a suitable domain, and lim f(x) = lim h(x) = L, then lim g(x) = L.

x^2 - 1 <= x^2 - sin(x) <= x^2 + 1 for all x. What can you say about lim x^2 -1 and lim x^2 + 1 as x grows large without bound?
 

1. What is the definition of a limit?

The limit of a function at a certain point is the value that the function approaches as the input approaches that point.

2. How do you calculate a limit?

To calculate a limit, you must evaluate the function at values closer and closer to the point in question, and see what value the function is approaching.

3. How do you show that a limit is approaching infinity?

To show that a limit is approaching infinity, you must show that the function is growing without bound as the input approaches the point in question. In the case of the function x^2-sin(x), as x approaches infinity, the value of the function will also approach infinity.

4. What is the step-by-step process for calculating the limit of x^2-sin(x) as x approaches infinity?

The step-by-step process for calculating this limit is as follows:
1. Plug in larger and larger values for x, such as 100, 1000, 10000, etc.
2. Observe that as x gets larger, the value of the function also gets larger.
3. This indicates that the limit is approaching infinity.

5. Can you use a graph to show that the limit of x^2-sin(x) as x approaches infinity is infinity?

Yes, a graph can be used to show that the limit of x^2-sin(x) as x approaches infinity is infinity. If you plot the function on a graph, you will see that as x approaches infinity, the graph will continue to rise without bound, indicating that the limit is infinity.

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