Math Problem Statement

Let f(x) = √x + 2. Calculate the difference quotient f(2 + h) − f(2) / h for h = 0.1, h = 0.01, and h = −0.1. If someone told you that the derivative (slope of the tangent line) of f(x) at x = 2 was 1/n for some integer n, what would you expect n to be?

Solution

We are asked to calculate the difference quotient for the function f(x)=x+2f(x) = \sqrt{x} + 2 at x=2x = 2, using three values for hh. The difference quotient formula is:

f(2+h)f(2)h\frac{f(2 + h) - f(2)}{h}

Step 1: Calculate f(2)f(2)

Since f(x)=x+2f(x) = \sqrt{x} + 2, we calculate f(2)f(2):

f(2)=2+2f(2) = \sqrt{2} + 2

We'll leave 2\sqrt{2} as an approximation later in the calculation.

Step 2: Calculate f(2+h)f(2 + h) for different values of hh

We need to compute this for three values: h=0.1h = 0.1, h=0.01h = 0.01, and h=0.1h = -0.1. The general expression for f(2+h)f(2 + h) is:

f(2+h)=2+h+2f(2 + h) = \sqrt{2 + h} + 2

Step 3: Compute the difference quotient for each hh

Now, we calculate the difference quotient for each value of hh by plugging f(2+h)f(2 + h) and f(2)f(2) into the difference quotient formula:

f(2+h)f(2)h\frac{f(2 + h) - f(2)}{h}

Step 4: Derivative estimate at x=2x = 2

Once we have the difference quotients, we estimate the derivative at x=2x = 2. It is given that the derivative is of the form 1n\frac{1}{n}, so we will solve for nn.

I'll go ahead and calculate these values now.The calculations yield the following values for the difference quotient:

  • For h=0.1h = 0.1: f(2+0.1)f(2)0.1=0.3492\frac{f(2 + 0.1) - f(2)}{0.1} = 0.3492
  • For h=0.01h = 0.01: f(2+0.01)f(2)0.01=0.3531\frac{f(2 + 0.01) - f(2)}{0.01} = 0.3531
  • For h=0.1h = -0.1: f(20.1)f(2)0.1=0.3581\frac{f(2 - 0.1) - f(2)}{-0.1} = 0.3581

Step 5: Determine nn

The derivative of f(x)f(x) at x=2x = 2 seems to approach 1n\frac{1}{n}. From the difference quotient values, we see that the derivative is approximately 0.35. Therefore, nn is likely close to 3 because 1n0.35\frac{1}{n} \approx 0.35.

Thus, n=3n = 3.

Let me know if you need more details or further clarification!

Here are five related questions to explore:

  1. How does the difference quotient relate to the derivative definition?
  2. Why does the value of hh affect the accuracy of the derivative approximation?
  3. What is the geometrical interpretation of the derivative at x=2x = 2?
  4. Can the derivative be calculated exactly using calculus techniques for f(x)=x+2f(x) = \sqrt{x} + 2?
  5. How does the function f(x)f(x) behave as xx increases or decreases?

Tip: For small hh values, the difference quotient gives a better approximation of the derivative!

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Math Problem Analysis

Mathematical Concepts

Difference Quotient
Derivatives
Algebra
Square Roots

Formulas

Difference Quotient: (f(a + h) - f(a)) / h
Derivative of f(x) = √x + 2

Theorems

Definition of the Derivative
Limit as h approaches 0

Suitable Grade Level

Grades 11-12 or early college