Math Problem Statement

how do i approach this: if f(x) = sqrt(x+2) then lim h->0 (f(2+h)-f(2))/h =

Solution

This is a limit that involves the difference quotient, and it is essentially the definition of the derivative of the function f(x)f(x) at the point x=2x = 2. To approach this limit, we can follow these steps:

  1. Recall the definition of the derivative:
    The limit given is the definition of the derivative of f(x)f(x) at x=2x = 2: limh0f(2+h)f(2)h\lim_{h \to 0} \frac{f(2+h) - f(2)}{h} This is f(2)f'(2), the derivative of f(x)f(x) at x=2x = 2.

  2. Find the derivative of f(x)f(x):
    The function f(x)=x+2f(x) = \sqrt{x+2}. To find the derivative f(x)f'(x), we use the chain rule: f(x)=ddx(x+2)=12x+21f'(x) = \frac{d}{dx} \left( \sqrt{x+2} \right) = \frac{1}{2\sqrt{x+2}} \cdot 1 Therefore, f(x)=12x+2f'(x) = \frac{1}{2\sqrt{x+2}}.

  3. Evaluate the derivative at x=2x = 2:
    Now, substitute x=2x = 2 into the derivative: f(2)=122+2=124=12×2=14f'(2) = \frac{1}{2\sqrt{2+2}} = \frac{1}{2\sqrt{4}} = \frac{1}{2 \times 2} = \frac{1}{4}

Thus, the value of the limit is: limh0f(2+h)f(2)h=f(2)=14\lim_{h \to 0} \frac{f(2+h) - f(2)}{h} = f'(2) = \frac{1}{4}

Do you want further details or have any questions?

Here are 5 related questions that expand on this concept:

  1. How would you find the derivative of f(x)=xnf(x) = x^n using the limit definition?
  2. What is the general form of the derivative of f(x)=x+cf(x) = \sqrt{x + c}?
  3. How does the chain rule apply to composite functions like f(x)=g(x)f(x) = \sqrt{g(x)}?
  4. How do you approach the limit definition of the derivative when the function involves a fraction?
  5. What is the geometric interpretation of the derivative at a point?

Tip: When working with square root functions, remember to be careful with the chain rule since the derivative depends on the inner function as well!

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Math Problem Analysis

Mathematical Concepts

Calculus
Limit Definition
Derivatives

Formulas

Limit definition of derivative
Chain rule

Theorems

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Suitable Grade Level

Advanced High School / College