Math Problem Statement

where are the local min and loca max at?

Where are the local minima and local maxima of g(x) = ∫₀ˣ f(t) dt, based on the graph of f(x) provided?

Solution

To analyze this problem, we are tasked with identifying the local maxima and local minima of the function g(x)=0xf(t)dtg(x) = \int_0^x f(t) \, dt, where the graph of f(x)f(x) is provided.

Key Properties:

  1. g(x)=f(x)g'(x) = f(x), meaning the slope of g(x)g(x) is determined by f(x)f(x).
  2. Local maxima/minima of g(x)g(x) occur where f(x)=0f(x) = 0 (critical points) and where f(x)f(x) changes sign:
    • g(x)g(x) has a local maximum where f(x)f(x) changes from positive to negative.
    • g(x)g(x) has a local minimum where f(x)f(x) changes from negative to positive.

Observing the Graph:

  • The graph shows f(x)f(x) crossing the x-axis at several points in the interval [0,10][0, 10].
  • We now identify these critical points and analyze the sign changes of f(x)f(x):
  1. f(x)=0f(x) = 0 at x1.5x \approx 1.5, x4.5x \approx 4.5, x7x \approx 7, and x9.5x \approx 9.5.

Sign Analysis and Classification:

  • Between x=0x = 0 and x1.5x \approx 1.5, f(x)>0f(x) > 0: g(x)g(x) increases.
  • At x1.5x \approx 1.5, f(x)f(x) changes from positive to negative: local maximum.
  • Between x1.5x \approx 1.5 and x4.5x \approx 4.5, f(x)<0f(x) < 0: g(x)g(x) decreases.
  • At x4.5x \approx 4.5, f(x)f(x) changes from negative to positive: local minimum.
  • Between x4.5x \approx 4.5 and x7x \approx 7, f(x)>0f(x) > 0: g(x)g(x) increases.
  • At x7x \approx 7, f(x)f(x) changes from positive to negative: local maximum.
  • Between x7x \approx 7 and x9.5x \approx 9.5, f(x)<0f(x) < 0: g(x)g(x) decreases.
  • At x9.5x \approx 9.5, f(x)f(x) changes from negative to positive: local minimum.

Final Answer:

  • Local maxima: x1.5x \approx 1.5, x7x \approx 7
  • Local minima: x4.5x \approx 4.5, x9.5x \approx 9.5

Would you like a more detailed explanation or help with related concepts?


5 Follow-Up Questions:

  1. Can you explain why g(x)g(x) is an antiderivative of f(x)f(x)?
  2. How would the integral g(x)g(x) behave if f(x)f(x) stayed entirely positive on [0,10][0, 10]?
  3. What would happen to the maxima and minima if f(x)f(x) were shifted upward or downward?
  4. How does the Fundamental Theorem of Calculus relate to this problem?
  5. Can you determine the total change in g(x)g(x) over the interval [0,10][0, 10]?

Tip:

Always link the critical points of a graph to where its derivative (or related function) changes sign—this is essential for finding maxima and minima!

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Critical Points
Sign Changes

Formulas

g'(x) = f(x)
Local maxima/minima conditions based on derivative sign changes

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12 or early college