Math Problem Statement

Lim——>1 x^3-1/x-1

Solution

The limit you're trying to evaluate is:

limx1x31x1\lim_{{x \to 1}} \frac{x^3 - 1}{x - 1}

If we substitute x=1x = 1 directly, both the numerator and denominator become 0, resulting in an indeterminate form 00\frac{0}{0}. To resolve this, we can factor the numerator.

Step 1: Factor the numerator

We can factor x31x^3 - 1 as a difference of cubes:

x31=(x1)(x2+x+1)x^3 - 1 = (x - 1)(x^2 + x + 1)

Step 2: Simplify the expression

Now, substitute the factored form of the numerator into the original limit:

x31x1=(x1)(x2+x+1)x1\frac{x^3 - 1}{x - 1} = \frac{(x - 1)(x^2 + x + 1)}{x - 1}

Since x1x - 1 appears in both the numerator and denominator, we can cancel them out (as long as x1x \neq 1):

=x2+x+1= x^2 + x + 1

Step 3: Evaluate the limit

Now, we can directly substitute x=1x = 1 into the simplified expression:

12+1+1=31^2 + 1 + 1 = 3

Thus, the limit is:

limx1x31x1=3\lim_{{x \to 1}} \frac{x^3 - 1}{x - 1} = 3

Let me know if you need more details or have any questions!

Here are 5 related questions to expand your understanding:

  1. How would you compute limx2x38x2\lim_{{x \to 2}} \frac{x^3 - 8}{x - 2}?
  2. What is the general formula for factoring a difference of cubes?
  3. Can you apply L'Hopital's Rule to evaluate limx1x31x1\lim_{{x \to 1}} \frac{x^3 - 1}{x - 1}?
  4. What happens if you apply direct substitution to limits involving indeterminate forms like 00\frac{0}{0}?
  5. How does the factorization technique change for higher powers of xx, like x41x^4 - 1?

Tip: When you encounter a limit with an indeterminate form 00\frac{0}{0}, try factoring or using L'Hopital's Rule to resolve it.

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Algebra
Factoring Cubic Polynomials

Formulas

Difference of cubes: x^3 - a^3 = (x - a)(x^2 + ax + a^2)
Limit evaluation: lim (x -> c) f(x)/g(x)

Theorems

Difference of cubes
Indeterminate forms (0/0)
L'Hopital's Rule (optional)

Suitable Grade Level

Grades 11-12, College Calculus 1