Math Problem Statement

find all asymptotes for f(x) = x 2 (e 1/x − 1)

Solution

To find all the asymptotes of the function f(x)=x2(e1x1)f(x) = x^2 \left( e^{\frac{1}{x}} - 1 \right), we need to examine the behavior of the function as xx approaches specific values, usually xx \to \infty, xx \to -\infty, and near any points where the function might become undefined (e.g., vertical asymptotes).

Step 1: Investigate as xx \to \infty

As xx \to \infty, we have:

1x0\frac{1}{x} \to 0

Thus, e1xe0=1e^{\frac{1}{x}} \to e^0 = 1, and so:

f(x)=x2(e1x1)x2(11)=0f(x) = x^2 (e^{\frac{1}{x}} - 1) \to x^2 (1 - 1) = 0

Therefore, the function tends to 0 as xx \to \infty, indicating that the horizontal asymptote is:

y = 0 \quad \text{(as x \to \infty)}

Step 2: Investigate as xx \to -\infty

As xx \to -\infty, similarly, 1x0\frac{1}{x} \to 0 and e1xe0=1e^{\frac{1}{x}} \to e^0 = 1. So:

f(x)=x2(e1x1)x2(11)=0f(x) = x^2 (e^{\frac{1}{x}} - 1) \to x^2 (1 - 1) = 0

Thus, there is also a horizontal asymptote at:

y = 0 \quad \text{(as x \to -\infty)}

Step 3: Investigate as x0+x \to 0^+ (from the right side of 0)

As x0+x \to 0^+, 1x\frac{1}{x} \to \infty, so e1xe^{\frac{1}{x}} \to \infty. Thus:

f(x)=x2(e1x1)x2e1xf(x) = x^2 \left( e^{\frac{1}{x}} - 1 \right) \sim x^2 \cdot e^{\frac{1}{x}}

Since e1xe^{\frac{1}{x}} \to \infty much faster than x2x^2 decreases, f(x)f(x) \to \infty as x0+x \to 0^+. Therefore, there is no vertical asymptote as x0+x \to 0^+, but the function diverges to infinity.

Step 4: Investigate as x0x \to 0^- (from the left side of 0)

As x0x \to 0^-, 1x\frac{1}{x} \to -\infty, so e1x0e^{\frac{1}{x}} \to 0. Therefore:

f(x)=x2(e1x1)x2(1)=x2f(x) = x^2 \left( e^{\frac{1}{x}} - 1 \right) \sim x^2 \cdot (-1) = -x^2

Thus, as x0x \to 0^-, f(x)0f(x) \to 0.

Conclusion:

  • Horizontal asymptote: y=0y = 0 (both as xx \to \infty and xx \to -\infty).
  • No vertical asymptote at x=0x = 0, but the function diverges as x0+x \to 0^+.

Would you like more details or have any questions?


Here are 5 related questions:

  1. How do you find the derivative of f(x)=x2(e1/x1)f(x) = x^2(e^{1/x} - 1)?
  2. What are the critical points of the function?
  3. Can you determine the concavity of the function at different points?
  4. What happens to the function when xx approaches zero from both sides?
  5. Can you explore limits of other functions with e1/xe^{1/x} terms?

Tip: Always check both sides of a function near potential vertical asymptotes for more precise behavior.

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Math Problem Analysis

Mathematical Concepts

Asymptotes
Limits
Exponential Functions

Formulas

Limit as x → ∞: f(x) = x^2 (e^{1/x} - 1)
Limit as x → -∞: f(x) = x^2 (e^{1/x} - 1)
Limit as x → 0^+: f(x) ≈ x^2 e^{1/x}
Limit as x → 0^-: f(x) ≈ -x^2

Theorems

Asymptote theorem: behavior of functions as x approaches infinity or negative infinity
Exponential Growth: the behavior of e^{1/x} as x → 0

Suitable Grade Level

Grades 11-12 or early college