Evaluate the limit lim x->1 of (x^3 - 1)/(x - 1).

Practice Questions

Q1
Evaluate the limit lim x->1 of (x^3 - 1)/(x - 1).
  1. 0
  2. 1
  3. 3
  4. 2

Questions & Step-by-Step Solutions

Evaluate the limit lim x->1 of (x^3 - 1)/(x - 1).
Correct Answer: 3
  • Step 1: Identify the limit we want to evaluate: lim x->1 of (x^3 - 1)/(x - 1).
  • Step 2: Notice that if we plug in x = 1 directly, both the numerator and denominator become 0, which is an indeterminate form.
  • Step 3: Factor the numerator (x^3 - 1). It can be factored as (x - 1)(x^2 + x + 1).
  • Step 4: Rewrite the limit using the factored form: lim x->1 of [(x - 1)(x^2 + x + 1)]/(x - 1).
  • Step 5: Cancel the (x - 1) terms in the numerator and denominator, as long as x is not equal to 1.
  • Step 6: Now we have lim x->1 of (x^2 + x + 1).
  • Step 7: Substitute x = 1 into the simplified expression: 1^2 + 1 + 1 = 3.
  • Step 8: Therefore, the limit is 3.
  • Limit Evaluation – Understanding how to evaluate limits, particularly when direct substitution leads to an indeterminate form.
  • Factoring Polynomials – The ability to factor polynomials to simplify expressions before taking limits.
  • L'Hôpital's Rule – An alternative method for evaluating limits that result in indeterminate forms, though not used in this solution.
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