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The Squeeze Theorem

The Squeeze Theorem

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The Squeeze Theorem: Solving Tricky Limits with Ease

When it comes to dealing with difficult limits, especially those involving oscillating or undefined points, calculus offers us useful techniques. One such technique is the Squeeze Theorem, also known as the Sandwich Theorem, which proves to be a lifesaver in these tricky situations.

What is the Squeeze Theorem?

The Squeeze Theorem states that if functions f, g, and h satisfy the condition , and for a constant L, then . In simpler terms, it states that a function f is "squeezed" between two other functions, g and h, which have the same limit at a particular point A.

Proving the Squeeze Theorem

In order to prove the Squeeze Theorem, we need to find a value for delta, such that whenever , we have where L is the evaluation of the limit as x approaches the point A.

Using absolute value laws, we can rewrite this as (1) and (2) for all x on some open interval containing A. Next, by definition, there exists some for all x on that interval. Using absolute value laws, we can rewrite this as (3) for all x on that interval. By combining (1), (2), and (3), we get . Using absolute value laws again, we can further simplify this to .

Informal Proof

In essence, the Squeeze Theorem confirms that as g and h are equal at the point A, and there is no room for f to take on any other value between them, we can say that .

When to Use the Squeeze Theorem Formula

The Squeeze Theorem should only be used as a last resort. It is always recommended to try solving limits through algebraic manipulation first. However, if that proves unsuccessful, the Squeeze Theorem can be applied, but only if . Keep in mind that it cannot be used if the limits are not equal.

Examples of Evaluating Limits Using the Squeeze Theorem

Let's examine a simple example to understand the application of the Squeeze Theorem. We need to verify that . As we substitute x=0, we get an undefined form, making it an ideal candidate for the Squeeze Theorem.

  • Step 1: Create a double-sided inequality based on the nature of the cosine function. Since cosine oscillates on the closed interval [-1, 1], we can write this as .
  • Step 2: Modify the inequality as needed. As our function is , we multiply our double-sided inequality by to get .
  • Step 3: Check if our function is bounded. As our function is bounded, we now need to verify that in order to apply the Squeeze Theorem.
  • Step 4: Apply the Squeeze Theorem. Since , the Squeeze Theorem can be applied, and we get .

Let's try another example: Find .

  • Step 1: Create a double-sided inequality based on the nature of the sine function. As sine also oscillates on the closed interval [-1, 1], we can write this as .
  • Step 2: Modify the inequality as needed. Our function is , and our double-sided inequality is , so we multiply it by and get .
  • Step 3: Check if our function is bounded. As our function is bounded, we now need to verify that in order to apply the Squeeze Theorem.
  • Step 4: Apply the Squeeze Theorem. Since , the Squeeze Theorem can be applied, and we get .

Key Takeaways from The Squeeze Theorem

  • The Squeeze Theorem is a valuable method for solving limits that cannot be evaluated through algebraic manipulation.
  • The theorem states that if functions f, g, and h satisfy the condition , and for a constant L, then .
  • The Squeeze Theorem can only be applied if the conditions and are met.
  • The general strategy for solving limits using the Squeeze Theorem is to start with the trig function and then work up towards the function in question.

Solving Limits Made Easy: The Squeeze Theorem

Limits can be challenging to solve, especially when traditional methods fail. But with the help of the Squeeze Theorem, tricky limits can be conquered. This powerful theorem allows for the evaluation of limits by "squeezing" the original function between two known functions.

Understanding the Squeeze Theorem

The Squeeze Theorem states that if a function lies between two other functions as x approaches a certain value, and those two functions have the same limit at that value, then the original function must also have that limit.

Now let's take a look at how to apply the Squeeze Theorem in four simple steps:

  • Step 1: Set up a double-sided inequality based on the nature of the original function.
  • Step 2: Make any necessary adjustments to the inequality.
  • Step 3: Evaluate the limits on both sides of the inequality to ensure they are equal.
  • Step 4: Apply the Squeeze Theorem to find the limit of the original function.

By following this process, even the most difficult limits can be solved with ease.

Exceptions to the Rule

While the Squeeze Theorem is a powerful tool, it does have its limits. This method cannot be used if the two-sided limit does not exist. In simpler terms, if the left-hand and right-hand limits are not equivalent, the Squeeze Theorem cannot be applied.

In Conclusion

The Squeeze Theorem provides a helpful alternative when traditional methods fail to solve limits. By following the four simple steps outlined above, you can conquer even the most complex limits with confidence. Happy calculating!

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