Math Problem Statement

If f and g are the functions whose graphs are shown, let u(x) = f(g(x)), v(x) = g(f(x)), and w(x) = g(g(x)). Find each derivative, if it exists. If it does not exist, explain why.

Solution

Let's analyze the problem step by step based on the given graph and information.

The question is asking to find derivatives of the functions defined by:

  • u(x)=f(g(x))u(x) = f(g(x)),
  • v(x)=g(f(x))v(x) = g(f(x)),
  • w(x)=g(g(x))w(x) = g(g(x)).

(a) Finding u(1)=ddx[f(g(x))]u'(1) = \frac{d}{dx}[f(g(x))] at x=1x = 1

By the chain rule, the derivative of u(x)u(x) is: u(x)=f(g(x))g(x)u'(x) = f'(g(x)) \cdot g'(x) Now, let's plug in x=1x = 1: u(1)=f(g(1))g(1)u'(1) = f'(g(1)) \cdot g'(1) From the graph:

  • g(1)=5g(1) = 5 (from the blue curve at x=1x = 1).
  • We now need f(5)f'(5) and g(1)g'(1):
    • f(5)f'(5): At x=5x = 5, the red graph (representing f(x)f(x)) has a sharp corner, indicating that the derivative does not exist at x=5x = 5.
    • g(1)g'(1): From the blue graph at x=1x = 1, the slope appears to be 0, as it is a flat horizontal line.

Thus, u(1)u'(1) does not exist because f(5)f'(5) does not exist.

(b) Finding v(1)=ddx[g(f(x))]v'(1) = \frac{d}{dx}[g(f(x))] at x=1x = 1

Using the chain rule again: v(x)=g(f(x))f(x)v'(x) = g'(f(x)) \cdot f'(x) Now, evaluate at x=1x = 1: v(1)=g(f(1))f(1)v'(1) = g'(f(1)) \cdot f'(1) From the graph:

  • f(1)=1f(1) = 1 (from the red curve at x=1x = 1),
  • Therefore, we need g(1)g'(1) and f(1)f'(1):
    • g(1)=0g'(1) = 0 (as previously noted, the blue graph is flat at x=1x = 1).
    • f(1)f'(1): At x=1x = 1, the red graph has a positive slope of 1.

Thus, since g(1)=0g'(1) = 0, v(1)=0v'(1) = 0.

(c) Finding w(1)=ddx[g(g(x))]w'(1) = \frac{d}{dx}[g(g(x))] at x=1x = 1

Again, by the chain rule: w(x)=g(g(x))g(x)w'(x) = g'(g(x)) \cdot g'(x) At x=1x = 1: w(1)=g(g(1))g(1)w'(1) = g'(g(1)) \cdot g'(1) From the graph:

  • g(1)=5g(1) = 5,
  • We need g(5)g'(5) and g(1)g'(1):
    • g(1)=0g'(1) = 0 (flat blue curve at x=1x = 1),
    • g(5)g'(5): The blue graph has a sharp corner at x=5x = 5, so the derivative g(5)g'(5) does not exist.

Thus, w(1)w'(1) does not exist because g(5)g'(5) does not exist.

Final Answers:

  • (a) u(1)u'(1) does not exist because f(5)f'(5) does not exist.
  • (b) v(1)=0v'(1) = 0.
  • (c) w(1)w'(1) does not exist because g(5)g'(5) does not exist.

Let me know if you want further details on any part of the solution!

Here are 5 related questions:

  1. How is the chain rule applied to composite functions like f(g(x))f(g(x))?
  2. What does it mean for a derivative to not exist at a corner?
  3. How can we estimate the slope from a graph visually?
  4. Why does g(1)=0g'(1) = 0 despite the function being defined?
  5. Can you describe a situation where a derivative exists but equals zero?

Tip: Sharp corners in a function's graph are key indicators that the derivative does not exist at that point.

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Math Problem Analysis

Mathematical Concepts

Calculus
Chain Rule
Derivatives
Graph Interpretation

Formulas

Chain rule for composite functions: (f(g(x)))' = f'(g(x)) * g'(x)
v'(x) = g'(f(x)) * f'(x)
w'(x) = g'(g(x)) * g'(x)

Theorems

Chain Rule for Derivatives

Suitable Grade Level

University Calculus I or II