Math Problem Statement

Question 1 (10 points) Consider a function f(x) with the following properties • • • • • f(x) is defined and continu- ous everywhere EXCEPT at x = −3. f has a vertical asymptote at x = −3. lim f(x)=2 x→−∞ limf(x)=−4 x→∞ f(x) is continuous but NOT differentiable at x = 5. • f′(x) > 0 on the interval (1, 5). • f′(x) < 0 on the inter- vals (−∞,−3), (−3,1) and (5, ∞). • f′′(x) > 0 on the intervals (−3, 5) and (5, ∞). • f′′(x) < 0 on the interval (−∞, −3). a) (2 point) At what values of x does f have a local maximum (if any)? local minimum (if any)? b) (2 point) What are the x-coordinates of the inflection points of f (if any)? c) (6 points) Draw, on your own axes, a possible graph of a curve y = f(x).

Solution

Let's break down each part of this problem:

Given information about f(x)f(x):

  1. f(x)f(x) is continuous everywhere except at x=3x = -3, where it has a vertical asymptote.
  2. End behavior:
    • limxf(x)=2\lim_{x \to -\infty} f(x) = 2
    • limxf(x)=4\lim_{x \to \infty} f(x) = -4
  3. Continuity and differentiability:
    • f(x)f(x) is continuous but not differentiable at x=5x = 5.
  4. First derivative information (f(x)f'(x)):
    • f(x)>0f'(x) > 0 on (1,5)(1, 5), meaning f(x)f(x) is increasing on this interval.
    • f(x)<0f'(x) < 0 on (,3)(-\infty, -3), (3,1)(-3, 1), and (5,)(5, \infty), meaning f(x)f(x) is decreasing on these intervals.
  5. Second derivative information (f(x)f''(x)):
    • f(x)>0f''(x) > 0 on (3,5)(-3, 5) and (5,)(5, \infty), indicating concave up on these intervals.
    • f(x)<0f''(x) < 0 on (,3)(-\infty, -3), indicating concave down on this interval.

Part (a): Local Maximum and Minimum

To identify local maxima and minima, let's use the first derivative information, f(x)f'(x):

  • Decreasing on (,3)(-\infty, -3), increasing on (3,1)(-3, 1), and decreasing again on (1,5)(1, 5), with increasing on (5,)(5, \infty).
  1. Local Maximum: From the given intervals of increase and decrease:
    • The function changes from increasing to decreasing at x=5x = 5, so f(x)f(x) has a local maximum at x=5x = 5.

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Continuity
Differentiability
First Derivative Test
Second Derivative Test

Formulas

lim x → -∞ f(x)
lim x → ∞ f(x)
First Derivative Test: Change of sign in f'(x)
Second Derivative Test: Change of concavity based on f''(x)

Theorems

First Derivative Test for local extrema
Second Derivative Test for concavity and inflection points

Suitable Grade Level

Undergraduate Calculus