Evaluating Limits: Understanding the Solution to a Challenging Calculus Problem

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In summary, the individual is struggling with a limit problem in their calculus course and has tried factoring and substitution methods with no success. They are confused about the answer provided by an online solver and are seeking clarification on how that answer is possible. Another individual confirms that they also got an answer of 4/3 and cannot see how the online solver's answer is correct.
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NoLimits
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Hello, I am struggling with limits in my calculus course and would appreciate a bit of help. The question is:

[tex]\lim_{x→-6}\frac{x^2-8x+12}{x^2-x+30}[/tex]
So far I have tried the factoring and substitution methods but have not managed to match the answers given by online equation solvers. For example, when using direct substitution I get an answer of 4/3, whereas mathway (online solver) says the answer is x2-8x+12. Would someone please explain how that answer is possible? I've looked around online but nothing I've found seems to help in my understanding.
 
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NoLimits said:
Hello, I am struggling with limits in my calculus course and would appreciate a bit of help. The question is:

[tex]\lim_{x→-6}\frac{x^2-8x+12}{x^2-x+30}[/tex]
So far I have tried the factoring and substitution methods but have not managed to match the answers given by online equation solvers. For example, when using direct substitution I get an answer of 4/3, whereas mathway (online solver) says the answer is x2-8x+12. Would someone please explain how that answer is possible? I've looked around online but nothing I've found seems to help in my understanding.
I get a limit of 4/3 as well. There's no way that I can see that the limit could be what you say mathway gives.
 
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Thanks, I was driving myself crazy trying to figure out what I did wrong.
 

1. What is the purpose of evaluating limits in mathematics?

Evaluating limits is an essential concept in mathematics that helps us understand the behavior of a function at a particular point. It allows us to determine the value that a function approaches as its input approaches a specific value. This helps us understand the overall behavior of the function and make predictions about its behavior in other parts of the domain.

2. How do you evaluate limits?

There are various methods for evaluating limits, including algebraic manipulation, substitution, and graphical analysis. The most commonly used method is algebraic manipulation, where we use algebraic properties and theorems to simplify the expression and find the limit. Substitution involves substituting the value of the limit into the function and simplifying the resulting expression. Graphical analysis involves plotting the function and observing its behavior around the limit point.

3. What is the difference between left-sided and right-sided limits?

Left-sided limits and right-sided limits are used to evaluate the behavior of a function as its input approaches a specific value from the left or right. A left-sided limit is the value that a function approaches as its input approaches the specific value from the left side (values smaller than the specific value). Similarly, a right-sided limit is the value that a function approaches as its input approaches the specific value from the right side (values larger than the specific value).

4. Can a limit not exist?

Yes, a limit can fail to exist if the function approaches different values from the left and right sides of the specific value. This is known as a jump discontinuity. A limit can also fail to exist if the function approaches infinity or negative infinity as its input approaches the specific value. This is known as an infinite discontinuity.

5. How are limits used in real-world applications?

Limits have various real-world applications, such as in physics, engineering, and economics. For example, in physics, limits are used to determine the velocity and acceleration of an object at a specific point in time. In engineering, limits are used to calculate the stress and strain on a structure. In economics, limits are used to analyze supply and demand functions and determine optimal production levels.

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