Calculating the Limit for sqrt(x^2-9)

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In summary, the conversation discusses the process of finding the limit of the function sqrt(x^2-9) as x approaches 3. The solution involves evaluating the radical expression and determining that the limit is equal to 0. The requirements for a limit to exist are also discussed, with the conclusion that the limit in this case approaches the same y-value of 0 from both sides.
  • #1
moberry
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Homework Statement



lim sqrt(x^2-9)
x->3


Homework Equations



I understand that the radical will evaluate to 0. I am not sure if the answer to the limit is 0, or undefined


The Attempt at a Solution



lim sqrt((3)^2-9) = sqrt(9-9) sqrt(0) = 0
x->3


Thanks for your help.
 
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  • #2
What is the requirements for a limit to exists?
 
  • #3
Hootenanny said:
What is the requirements for a limit to exists?

The limit coming from both sides, must approach the same y-value. In this case 0. The function will never hit 0, but will get infinitely close. That would make the value of the limit 0??
 
  • #4
moberry said:
The limit coming from both sides, must approach the same y-value. In this case 0. The function will never hit 0, but will get infinitely close. That would make the value of the limit 0??
Correct :approve:
 
  • #5
Hootenanny said:
Correct :approve:

Good deal. I thought that was it. Wanted to be 100% sure.
 

1. What is the formula for calculating the limit of sqrt(x^2-9)?

The formula for calculating the limit of sqrt(x^2-9) is lim(x→∞) sqrt(x^2-9) = ∞.

2. How do you simplify the expression for calculating the limit of sqrt(x^2-9)?

To simplify the expression, you can first factor out the largest power of x in the square root, so the expression becomes lim(x→∞) x√(1-9/x^2). Then, you can apply the limit laws to simplify further.

3. Can the limit of sqrt(x^2-9) be negative?

No, the limit of sqrt(x^2-9) cannot be negative. As x approaches infinity, the value under the square root, x^2-9, will always be positive. Therefore, the limit will always be positive or infinite.

4. What is the significance of the expression sqrt(x^2-9) in calculus?

The expression sqrt(x^2-9) is significant in calculus because it represents the distance between a point (x,0) and the point (3,0) on the x-axis. It is also commonly used in finding the slope of a tangent line to a curve at a given point.

5. How does the value of x affect the limit of sqrt(x^2-9)?

The value of x has a significant impact on the limit of sqrt(x^2-9). As x approaches infinity, the limit will also approach infinity. However, as x approaches -3 or 3 from either the left or right side, the limit will approach 0.

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