Math Problem Statement

7/x^3-1 Evaluate the function for values of x that approach 1 from the left and from the right.

Solution

We are given the function:

f(x)=7x31f(x) = \frac{7}{x^3 - 1}

We need to evaluate the behavior of this function as xx approaches 1 from both the left (x1x \to 1^-) and the right (x1+x \to 1^+).

Step 1: Analyze the denominator

The denominator of the function is:

x31x^3 - 1

As x1x \to 1, the denominator becomes:

131=01^3 - 1 = 0

Thus, the denominator approaches zero as x1x \to 1, which indicates a potential vertical asymptote at x=1x = 1.

Step 2: Evaluate the limit as x1x \to 1^- (from the left)

As xx approaches 1 from the left, x31x^3 - 1 is slightly negative because x3x^3 is just less than 1. Therefore, the denominator x31x^3 - 1 approaches 0 from the negative side.

Thus, as x1x \to 1^-, f(x)f(x) behaves as:

f(x)7small negative numberf(x) \approx \frac{7}{\text{small negative number}} \to -\infty

So:

limx17x31=\lim_{x \to 1^-} \frac{7}{x^3 - 1} = -\infty

Step 3: Evaluate the limit as x1+x \to 1^+ (from the right)

As xx approaches 1 from the right, x31x^3 - 1 is slightly positive because x3x^3 is just greater than 1. Therefore, the denominator x31x^3 - 1 approaches 0 from the positive side.

Thus, as x1+x \to 1^+, f(x)f(x) behaves as:

f(x)7small positive number+f(x) \approx \frac{7}{\text{small positive number}} \to +\infty

So:

limx1+7x31=+\lim_{x \to 1^+} \frac{7}{x^3 - 1} = +\infty

Conclusion:

  • As x1x \to 1^-, the function approaches -\infty.
  • As x1+x \to 1^+, the function approaches ++\infty.

This confirms that there is a vertical asymptote at x=1x = 1, with the function diverging to negative infinity from the left and positive infinity from the right.

Would you like a detailed breakdown of the steps? If so, feel free to ask!

Here are 5 related questions for further exploration:

  1. How do you find the horizontal asymptotes of rational functions?
  2. What is the significance of limits in understanding function behavior near asymptotes?
  3. Can you use L'Hopital's Rule to solve limits of indeterminate forms?
  4. What is the difference between a vertical and a horizontal asymptote?
  5. How do you analyze the behavior of polynomial functions near roots?

Tip: Always check both left-hand and right-hand limits when investigating vertical asymptotes!

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Math Problem Analysis

Mathematical Concepts

Limits
Asymptotic Behavior
Vertical Asymptotes

Formulas

f(x) = 7/(x^3 - 1)

Theorems

Limit Theorem
Asymptote Theorem

Suitable Grade Level

Grades 11-12 (Pre-Calculus, Calculus)