Math Problem Statement

Use the figure below to estimate the indicated derivatives, or state that they do not exist. Let h(x) = f(x) * g(x). Find h'(1), h'(2), and h'(3).

Solution

To solve this problem, we need to calculate the derivatives of the product h(x)=f(x)g(x)h(x) = f(x) \cdot g(x) at specific points: x=1x = 1, x=2x = 2, and x=3x = 3.

We will apply the product rule for differentiation: h(x)=f(x)g(x)+f(x)g(x)h'(x) = f'(x)g(x) + f(x)g'(x)

Steps:

  1. Estimate f(x)f(x) and g(x)g(x) values: We will estimate the values of the functions f(x)f(x) and g(x)g(x) by observing their respective graphs at x=1x = 1, x=2x = 2, and x=3x = 3.

  2. Estimate f(x)f'(x) and g(x)g'(x) derivatives: From the graphs, we will estimate the slopes of the functions at x=1x = 1, x=2x = 2, and x=3x = 3. For x=2x = 2, the derivative does not exist for f(x)f(x) because of the sharp corner.

  3. Substitute the values into the product rule and calculate the derivative.


Part A: h(1)h'(1)

  • From the graph:

    • f(1)=1f(1) = 1, g(1)=0g(1) = 0 (from their respective points on the graph).
    • The slopes at x=1x = 1:
      • f(1)f'(1) (slope of f(x)f(x)) is 2020=1\frac{2-0}{2-0} = 1.
      • g(1)g'(1) (slope of g(x)g(x)) is 0(1)20=12\frac{0 - (-1)}{2 - 0} = \frac{1}{2}.

    Now applying the product rule: h(1)=f(1)g(1)+f(1)g(1)=1(0)+1(12)=12h'(1) = f'(1)g(1) + f(1)g'(1) = 1(0) + 1\left(\frac{1}{2}\right) = \frac{1}{2}

Part B: h(2)h'(2)

  • f(x)f(x) has a sharp corner at x=2x = 2, meaning the derivative f(2)f'(2) does not exist. Therefore: h(2)=DNEh'(2) = \text{DNE}

Part C: h(3)h'(3)

  • From the graph:

    • f(3)=1f(3) = 1, g(3)=1g(3) = -1.
    • The slopes at x=3x = 3:
      • f(3)f'(3) (slope of f(x)f(x)) is 0242=1\frac{0 - 2}{4 - 2} = -1.
      • g(3)g'(3) (slope of g(x)g(x)) is 1042=12\frac{-1 - 0}{4 - 2} = -\frac{1}{2}.

    Now applying the product rule: h(3)=f(3)g(3)+f(3)g(3)=(1)(1)+1(12)=112=12h'(3) = f'(3)g(3) + f(3)g'(3) = (-1)(-1) + 1\left(-\frac{1}{2}\right) = 1 - \frac{1}{2} = \frac{1}{2}

Final Answers:

  • A. h(1)=12h'(1) = \frac{1}{2}
  • B. h(2)=DNEh'(2) = \text{DNE}
  • C. h(3)=12h'(3) = \frac{1}{2}

Do you have any questions or would you like further details?


Here are 5 related questions to deepen your understanding:

  1. How do we calculate the derivative of a product of two functions using the product rule?
  2. Why does a sharp corner cause the derivative to not exist at a point?
  3. What is the difference between a sharp corner and a discontinuity when determining derivatives?
  4. How can we estimate the slope of a graph visually when calculating derivatives?
  5. Can the derivative of a product exist if one of the factors has a discontinuity?

Tip: Always be cautious when identifying points where the derivative does not exist. Corners, cusps, and vertical tangents are common causes for this.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Derivatives
Product Rule
Graph Analysis

Formulas

h'(x) = f'(x)g(x) + f(x)g'(x)

Theorems

Product Rule for Derivatives

Suitable Grade Level

Grades 11-12, Calculus