Math Problem Statement

Consider the following function. (If an answer does not exist, enter DNE.)

f(x) = e−2⁄x

(a)

Find the vertical asymptote(s). (Enter your answers as a comma-separated list.)

x =

0

Find the horizontal asymptote(s). (Enter your answers as a comma-separated list.)

y =

1

(b)

Find the interval(s) of increase. (Enter your answer using interval notation.)

(−∞,0)∪(0,∞)

Find the interval(s) of decrease. (Enter your answer using interval notation.)

dne

(c)

Find the local maximum and minimum values.

local maximum value

dne

local minimum value

dne

(d)

Find the interval(s) on which f is concave up. (Enter your answer using interval notation.)

Find the interval(s) on which f is concave down. (Enter your answer using interval notation.)

Find the inflection point.

(xy) =

Solution

Let's analyze the given function f(x)=e2/xf(x) = e^{-2/x}:

(a) Vertical and Horizontal Asymptotes

  1. Vertical Asymptotes:

    • The function f(x)=e2/xf(x) = e^{-2/x} is undefined at x=0x = 0, so there is a vertical asymptote at x=0x = 0.

    Answer: x=0x = 0

  2. Horizontal Asymptotes:

    • As xx \to \infty, 2x0\frac{-2}{x} \to 0, and e0=1e^0 = 1. Hence, y=1y = 1 is a horizontal asymptote.
    • Similarly, as xx \to -\infty, 2x0\frac{-2}{x} \to 0, and e0=1e^0 = 1. Hence, y=1y = 1 is also the horizontal asymptote.

    Answer: y=1y = 1


(b) Intervals of Increase and Decrease

To find the intervals of increase and decrease:

  1. Compute the derivative of f(x)f(x): f(x)=e2/x2x2f'(x) = e^{-2/x} \cdot \frac{2}{x^2}

  2. Analyze f(x)f'(x):

    • For x>0x > 0, f(x)>0f'(x) > 0 (positive), so f(x)f(x) is increasing on (0,)(0, \infty).
    • For x<0x < 0, f(x)>0f'(x) > 0 (positive), so f(x)f(x) is also increasing on (,0)(-\infty, 0).

    Intervals of Increase: (,0)(0,)(-\infty, 0) \cup (0, \infty)
    Intervals of Decrease: DNE (none)\text{DNE (none)}


(c) Local Maximum and Minimum Values

  • Since f(x)f(x) is increasing everywhere in its domain, there are no local maximum or minimum values.

    Local Maximum Value: DNE
    Local Minimum Value: DNE


(d) Concavity and Inflection Points

To find concavity and inflection points:

  1. Compute the second derivative of f(x)f(x): f(x)=e2/x(4x3)+e2/x4x4f''(x) = e^{-2/x} \cdot \left(-\frac{4}{x^3}\right) + e^{-2/x} \cdot \frac{4}{x^4} Factorize: f(x)=e2/x4x4(x+1)f''(x) = e^{-2/x} \cdot \frac{4}{x^4} \cdot (-x + 1)

  2. Analyze f(x)f''(x):

    • f(x)>0f''(x) > 0 (concave up) when x>1x > 1 or x<0x < 0.
    • f(x)<0f''(x) < 0 (concave down) when 0<x<10 < x < 1.

    Intervals of Concave Up: (,0)(1,)(-\infty, 0) \cup (1, \infty)
    Intervals of Concave Down: (0,1)(0, 1)

  3. Inflection Point:

    • The concavity changes at x=1x = 1. Substitute x=1x = 1 into f(x)f(x): f(1)=e2/1=e2f(1) = e^{-2/1} = e^{-2}
    • Inflection point: (1,e2)(1, e^{-2}).

Final Answers:

(a)

  • Vertical Asymptote(s): x=0x = 0
  • Horizontal Asymptote(s): y=1y = 1

(b)

  • Interval(s) of Increase: (,0)(0,)(-\infty, 0) \cup (0, \infty)
  • Interval(s) of Decrease: DNE

(c)

  • Local Maximum Value: DNE
  • Local Minimum Value: DNE

(d)

  • Interval(s) of Concave Up: (,0)(1,)(-\infty, 0) \cup (1, \infty)
  • Interval(s) of Concave Down: (0,1)(0, 1)
  • Inflection Point: (1,e2)(1, e^{-2})

Let me know if you have questions or need further clarifications!

Here are some follow-up questions to explore:

  1. What happens to f(x)f(x) as xx approaches the vertical asymptote?
  2. How would shifting the function horizontally or vertically change the asymptotes?
  3. Can we generalize this analysis to f(x)=ea/xf(x) = e^{-a/x} for any constant aa?
  4. How does the concavity affect the overall graph shape?
  5. What happens to the intervals of increase if the sign of e2/xe^{-2/x} is flipped?

Tip: Always check for undefined points in the domain of a function to identify potential vertical asymptotes.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Exponential Functions
Asymptotes
Concavity and Inflection Points

Formulas

f'(x) = e^{-2/x} * (2/x^2)
f''(x) = e^{-2/x} * (4/x^4) * (-x + 1)

Theorems

First Derivative Test
Second Derivative Test

Suitable Grade Level

Undergraduate Calculus