Math Problem Statement

What is the value of lim(h → 0) [(16 + h)^(1/2) - 2] / h?

Solution

The problem you shared asks for the value of the following limit:

limh0(16+h)122h\lim_{h \to 0} \frac{(16+h)^{\frac{1}{2}} - 2}{h}

This expression is a derivative calculation in disguise. Let's break it down:

Step-by-Step Explanation:

  1. Recognize the form: This limit is the definition of the derivative of the function f(x)=xf(x) = \sqrt{x} at x=16x = 16. The formula for a derivative at a point aa is: f(a)=limh0f(a+h)f(a)hf'(a) = \lim_{h \to 0} \frac{f(a+h) - f(a)}{h} Here, f(x)=xf(x) = \sqrt{x}, so f(16)=16=4f(16) = \sqrt{16} = 4.

  2. Apply the definition of the derivative: limh016+h4h\lim_{h \to 0} \frac{\sqrt{16+h} - 4}{h} This matches the form we are given in the problem, except the 16+h4\sqrt{16+h} - 4 part is written as (16+h)122(16 + h)^{\frac{1}{2}} - 2 in the problem (since x=x1/2\sqrt{x} = x^{1/2} and 16=4\sqrt{16} = 4).

  3. Evaluate the limit: To solve the limit, we can rationalize the numerator by multiplying the numerator and denominator by the conjugate of the numerator: limh0(16+h)124h(16+h)12+4(16+h)12+4\lim_{h \to 0} \frac{(16+h)^{\frac{1}{2}} - 4}{h} \cdot \frac{(16+h)^{\frac{1}{2}} + 4}{(16+h)^{\frac{1}{2}} + 4} Simplifying the numerator using the difference of squares: limh0(16+h)16h((16+h)12+4)=limh0hh((16+h)12+4)\lim_{h \to 0} \frac{(16+h) - 16}{h((16+h)^{\frac{1}{2}} + 4)} = \lim_{h \to 0} \frac{h}{h((16+h)^{\frac{1}{2}} + 4)} The hh's cancel out: limh01(16+h)12+4\lim_{h \to 0} \frac{1}{(16+h)^{\frac{1}{2}} + 4} Now, substitute h=0h = 0: 116+4=14+4=18\frac{1}{\sqrt{16} + 4} = \frac{1}{4 + 4} = \frac{1}{8}

Final Answer:

limh0(16+h)124h=18\lim_{h \to 0} \frac{(16+h)^{\frac{1}{2}} - 4}{h} = \frac{1}{8}

Would you like further clarification or details? Here are some related questions to explore:

  1. What is the general form of a derivative using limits?
  2. How can rationalizing the numerator help in evaluating limits?
  3. Why do we cancel out hh in the fraction after rationalizing?
  4. What is the significance of evaluating limits when h0h \to 0?
  5. How would this process change if the base value x=16x = 16 were different?

Tip: Always check if a limit corresponds to the derivative definition. This helps simplify evaluation!

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Math Problem Analysis

Mathematical Concepts

Limits
Derivatives
Algebra

Formulas

lim(h → 0) [f(a + h) - f(a)] / h
Difference of squares

Theorems

Definition of a derivative

Suitable Grade Level

Grades 11-12, Calculus