Math Problem Statement

lim h->0 ((8+h)^1/3 -2)/h

Solution

We are tasked with finding the limit:

limh0(8+h)1/32h\lim_{h \to 0} \frac{(8+h)^{1/3} - 2}{h}

This is a typical problem involving limits and derivatives. Specifically, this limit can be interpreted as the derivative of the function f(x)=x1/3f(x) = x^{1/3} at x=8x = 8.

Solution:

We need to evaluate this limit using the following steps:

  1. Recognize the form: The expression resembles the definition of a derivative. It can be written as:

f(8)=limh0f(8+h)f(8)hf'(8) = \lim_{h \to 0} \frac{f(8+h) - f(8)}{h}

where f(x)=x1/3f(x) = x^{1/3} and f(8)=2f(8) = 2 since 81/3=28^{1/3} = 2.

  1. Differentiate f(x)=x1/3f(x) = x^{1/3}: Using the power rule for derivatives ddx(xn)=nxn1\frac{d}{dx}(x^n) = n x^{n-1}, the derivative of f(x)=x1/3f(x) = x^{1/3} is:

f(x)=13x2/3f'(x) = \frac{1}{3} x^{-2/3}

  1. Evaluate the derivative at x=8x = 8:

f(8)=1382/3f'(8) = \frac{1}{3} \cdot 8^{-2/3}

We know that 81/3=28^{1/3} = 2, so:

f(8)=13122=1314=112f'(8) = \frac{1}{3} \cdot \frac{1}{2^2} = \frac{1}{3} \cdot \frac{1}{4} = \frac{1}{12}

Conclusion:

Thus, the value of the limit is:

limh0(8+h)1/32h=112\lim_{h \to 0} \frac{(8+h)^{1/3} - 2}{h} = \frac{1}{12}


Would you like more details on any of the steps, or do you have any further questions?

Here are 5 related questions to explore further:

  1. What is the derivative of f(x)=xnf(x) = x^{n} for other powers of nn?
  2. How can limits be used to calculate the slope of a curve at a point?
  3. What are some other real-world applications of the derivative?
  4. How does the limit definition of a derivative apply to other functions?
  5. What is the geometric interpretation of a derivative at a given point?

Tip: When evaluating limits, especially those resembling the definition of the derivative, recognizing the pattern can save significant calculation time.

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Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Power Rule

Formulas

Derivative definition: f'(x) = lim(h -> 0) [(f(x+h) - f(x)) / h]
Power Rule for derivatives: d/dx(x^n) = n * x^(n-1)

Theorems

Limit definition of a derivative
Power Rule for differentiation

Suitable Grade Level

Grades 11-12 (Calculus)