Math Problem Statement

Let f(x) = 9 x3 − 1

and consider the limits lim x→1− f(x) and lim x→1+ f(x). (a) Use a table of values to evaluate f(x) = 9 x3 − 1 for values of x that approach 1 from the left and from the right. (Round your answers to one decimal place.) x f(x) x f(x) 0.5 -10.3

Correct: Your answer is correct. 1.5 27.2

Incorrect: Your answer is incorrect. 0.9 -33.2

Correct: Your answer is correct. 1.1 297.0

Incorrect: Your answer is incorrect. 0.99 -303.0

Changed: Your submitted answer was incorrect. Your current answer has not been submitted. 1.01 2997.0

Incorrect: Your answer is incorrect. 0.999 -3003.0

Changed: Your submitted answer was incorrect. Your current answer has not been submitted. 1.001 29997.0

Incorrect: Your answer is incorrect. 0.9999 -30003.0

Correct: Your answer is correct. 1.0001 299997

0.99999

Correct: Your answer is correct. 1.00001 2999997

Incorrect: Your answer is incorrect.

Solution

Let's first analyze the function:

f(x)=9x31f(x) = \frac{9}{x^3 - 1}

We are interested in evaluating the left-hand limit limx1f(x)\lim_{x \to 1^-} f(x) and the right-hand limit limx1+f(x)\lim_{x \to 1^+} f(x). To do this, we'll examine the behavior of f(x)f(x) near x=1x = 1 by substituting values approaching 1 from the left (e.g., 0.5, 0.9, 0.99, etc.) and from the right (e.g., 1.5, 1.1, 1.01, etc.).

Function Breakdown:

The function can be rewritten as: f(x)=9(x1)(x2+x+1)f(x) = \frac{9}{(x-1)(x^2+x+1)} Thus, f(x)f(x) has a discontinuity at x=1x = 1 because the denominator approaches zero as xx approaches 1.

For the Left-Hand Limit x1x \to 1^-:

  • As x1x \to 1^-, x1x - 1 becomes a small negative number, and (x2+x+1)(x^2 + x + 1) is positive, so the overall expression for f(x)f(x) tends to negative infinity.

For the Right-Hand Limit x1+x \to 1^+:

  • As x1+x \to 1^+, x1x - 1 becomes a small positive number, and (x2+x+1)(x^2 + x + 1) remains positive, so the overall expression for f(x)f(x) tends to positive infinity.

Now let's use the table values provided to evaluate the function near x=1x = 1:

xf(x)
0.5-10.3
0.9-33.2
0.99-303.0
0.999-3003.0
0.9999-30003.0
1.0001299997
1.00129997.0
1.012997.0
1.1297.0
1.527.2

From this table, we observe the following:

  • As xx approaches 1 from the left (values like 0.9, 0.99, 0.999), the values of f(x)f(x) become very large negative numbers, indicating the left-hand limit tends to negative infinity.
  • As xx approaches 1 from the right (values like 1.1, 1.01, 1.0001), the values of f(x)f(x) become very large positive numbers, indicating the right-hand limit tends to positive infinity.

Thus:

  • limx1f(x)=\lim_{x \to 1^-} f(x) = -\infty
  • limx1+f(x)=+\lim_{x \to 1^+} f(x) = +\infty

Would you like to explore more details, or have any further questions on this?

Follow-up questions:

  1. How would the graph of f(x)=9x31f(x) = \frac{9}{x^3 - 1} behave near x=1x = 1?
  2. What happens if we take the limit of f(x)f(x) as xx approaches 1 from different directions, say from x=2x = 2 or x=0x = 0?
  3. Can we apply L'Hopital's Rule to evaluate the limit as x1x \to 1?
  4. How would the behavior change if the function were f(x)=1x31f(x) = \frac{1}{x^3 - 1} instead of 9x31\frac{9}{x^3 - 1}?
  5. What is the role of the cubic term x3x^3 in determining the limits?

Tip:

Always carefully consider the sign of the denominator as xx approaches the point where the function is undefined. It helps determine whether the function tends to ++\infty or -\infty.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Discontinuity
Rational Functions

Formulas

f(x) = 9 / (x^3 - 1)
f(x) = 9 / ((x - 1)(x^2 + x + 1))

Theorems

Limit laws
Discontinuity in rational functions

Suitable Grade Level

Grades 11-12