Evaluate the limit: lim (x->4) (x^2 - 16) / (x^2 - 5x + 6)

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Understand the Problem

The question requires us to evaluate the limit of a rational function as x approaches 4. This involves techniques such as factoring and simplifying to resolve any indeterminate forms.

Answer

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Steps to Solve

  1. Factor the numerator and denominator

Factor $x^2 - 16$ as a difference of squares, and factor the quadratic in the denominator. $$ x^2 - 16 = (x - 4)(x + 4) $$ $$ x^2 - 5x + 6 = (x - 2)(x - 3) $$

  1. Rewrite the limit expression

Substitute the factored forms into the limit expression:

$$ \lim_{x \to 4} \frac{(x - 4)(x + 4)}{(x - 2)(x - 3)} $$

  1. Check for direct substitution

If we directly substitute $x = 4$ into the expression we obtain: $$ \frac{(4 - 4)(4 + 4)}{(4 - 2)(4 - 3)} = \frac{0 \cdot 8}{2 \cdot 1} = \frac{0}{2} = 0 $$

  1. State the final answer

Since direct substitution does not result in an indeterminate form, the limit is 0.

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More Information

The function converges to 0 as x approaches 4.

Tips

A common mistake is to incorrectly factor the quadratic expressions. Another mistake is to assume that since the numerator contains $(x-4)$, the limit automatically does not exist or is indeterminate. However, here the denominator does not have this factor, and direct substitution gives us the limit.

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