Math Problem Statement
Limit of ³√x minus 2 divided by x minus 8 as x approaches 8
Solution
To find the limit of as approaches 8, we'll follow these steps:
Step 1: Direct Substitution
First, substitute directly into the expression:
This results in an indeterminate form , so we need to use another method to evaluate the limit.
Step 2: Rationalize the Numerator
To resolve the indeterminate form, we can multiply the numerator and the denominator by the conjugate of the numerator's cube root, using the identity:
Let and . Then:
[ a^3 - b^3 = x - 8 = (\sqrt[3]{x} - 2)(\sqrt[3]{x^2} + 2\sqrt[3]{x} + 4) ]
So,
[ \frac{\sqrt[3]{x} - 2}{x - 8} = \frac{(\sqrt[3]{x} - 2)(\sqrt[3]{x^2} + 2\sqrt[3]{x} + 4)}{(x - 8)(\sqrt[3]{x^2} + 2\sqrt[3]{x} + 4)} ]
Since , the expression simplifies to:
[ \frac{1}{\sqrt[3]{x^2} + 2\sqrt[3]{x} + 4} ]
Step 3: Take the Limit
Now, substitute into the simplified expression:
[ \lim_{x \to 8} \frac{1}{\sqrt[3]{x^2} + 2\sqrt[3]{x} + 4} = \frac{1}{\sqrt[3]{8^2} + 2\sqrt[3]{8} + 4} = \frac{1}{\sqrt[3]{64} + 2 \times 2 + 4} = \frac{1}{4 + 4 + 4} = \frac{1}{12} ]
Final Answer
The limit is:
Would you like any details or have further questions?
Here are five related questions you might find interesting:
- How would you evaluate ?
- Can L'Hôpital's Rule be used to solve this limit problem?
- What is the geometric interpretation of limits in calculus?
- How do you find the limit of a function as approaches infinity?
- What are other methods to resolve indeterminate forms besides rationalization?
Tip: When you encounter indeterminate forms, always consider algebraic manipulation, such as rationalization or factoring, before resorting to more advanced techniques.
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Math Problem Analysis
Mathematical Concepts
Limits
Rationalization
Indeterminate Forms
Formulas
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Theorems
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Suitable Grade Level
Undergraduate
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