Math Problem Statement

if the deritive of f(x) = lim as h goes to zero of (the cube root of (8+6h+h^2)-2)/h what is f(x)

Solution

To find the function f(x)f(x) given its derivative in the form of a limit, we start with the expression:

f(x)=limh08+6h+h232hf'(x) = \lim_{h \to 0} \frac{\sqrt[3]{8 + 6h + h^2} - 2}{h}

This expression resembles the definition of the derivative using limits, suggesting it might be the derivative of a function evaluated at a specific point. Let's evaluate this limit step-by-step to identify the function f(x)f(x).

Step 1: Recognize the Expression

The expression inside the limit resembles the form of the derivative of the cube root function, x3\sqrt[3]{x}. More specifically, it looks like the derivative of f(x)=x3f(x) = \sqrt[3]{x} at some point.

Step 2: Identify the Point

The expression 8+6h+h23\sqrt[3]{8 + 6h + h^2} suggests that it is centered around the point where x=8x = 8. This is because when h=0h = 0, the cube root expression becomes 83=2\sqrt[3]{8} = 2.

Step 3: Set up the General Derivative Formula

The derivative of the cube root function, f(x)=x3f(x) = \sqrt[3]{x}, is:

f(x)=13x23f'(x) = \frac{1}{3} x^{-\frac{2}{3}}

Let's evaluate this derivative at x=8x = 8:

f(8)=13×823=13×14=112f'(8) = \frac{1}{3} \times 8^{-\frac{2}{3}} = \frac{1}{3} \times \frac{1}{4} = \frac{1}{12}

Step 4: Evaluate the Limit

We have previously identified that the given limit evaluates the derivative at the point x=8x = 8, and the limit should match this evaluation:

limh08+6h+h232h=112\lim_{h \to 0} \frac{\sqrt[3]{8 + 6h + h^2} - 2}{h} = \frac{1}{12}

Thus, the function f(x)f(x) whose derivative gives the limit expression is:

f(x)=x3f(x) = \sqrt[3]{x}

The derivative calculation above confirms that this matches the given limit, as the derivative of x3\sqrt[3]{x} evaluated at x=8x = 8 gives 112\frac{1}{12}.

Conclusion

Therefore, the function f(x)f(x) is:

f(x)=x3f(x) = \sqrt[3]{x}

Would you like to see more details, or do you have any questions about this explanation?


Here are some additional related questions you might find interesting:

  1. What is the derivative of f(x)=x3f(x) = \sqrt[3]{x} at x=1x = 1?
  2. How do you differentiate f(x)=x1/3f(x) = x^{1/3} using the power rule?
  3. Can you find the derivative of f(x)=x3+13f(x) = \sqrt[3]{x^3 + 1}?
  4. What is the derivative of g(x)=x23g(x) = \sqrt[3]{x^2}?
  5. How can you approximate 93\sqrt[3]{9} using the derivative of f(x)=x3f(x) = \sqrt[3]{x}?
  6. What are the critical points of f(x)=x3f(x) = \sqrt[3]{x}?
  7. How does the graph of f(x)=x3f(x) = \sqrt[3]{x} compare to g(x)=x1/3g(x) = x^{1/3}?
  8. How does the derivative of f(x)=x3f(x) = \sqrt[3]{x} help in understanding its concavity and inflection points?

Tip: To differentiate functions involving roots, consider rewriting them as powers, such as x1/3x^{1/3}, to apply the power rule easily.

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Math Problem Analysis

Mathematical Concepts

Limit
Derivative
Cube Root Function

Formulas

Definition of the derivative using limits
Derivative of cube root function

Theorems

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Suitable Grade Level

Grades 11-12