Limit Equivalence
1. The problem asks to find which statements are equivalent or true for the limit $$\lim_{x \to 2} \frac{x^2 + 2x - 8}{x^4 - 16}$$.
2. Start by factoring numerator and denominator:
- Numerator: $$x^2 + 2x - 8 = (x + 4)(x - 2)$$
- Denominator: $$x^4 - 16 = (x^2)^2 - 4^2 = (x^2 - 4)(x^2 + 4) = (x - 2)(x + 2)(x^2 + 4)$$
3. Substitute factored forms into the original limit:
$$\lim_{x \to 2} \frac{(x+4)(x-2)}{(x-2)(x+2)(x^2 + 4)}$$
4. Cancel the common factor $(x-2)$ from numerator and denominator, noting $x \to 2$ but $x \neq 2$:
$$\lim_{x \to 2} \frac{x+4}{(x+2)(x^2 + 4)}$$
This matches option a.
5. Evaluate the simplified limit by substituting $x=2$:
$$\frac{2+4}{(2+2)(2^2 + 4)} = \frac{6}{4 \cdot (4 + 4)} = \frac{6}{4 \cdot 8} = \frac{6}{32} = \frac{3}{16}$$
6. Check the given statements:
- a. $$\lim_{x \to 2} \frac{x+4}{(x+2)(x^2 + 4)}$$ is equivalent after simplification \(\checkmark\)
- b. $$\lim_{x \to 2} \frac{(x-4)(x+2)}{(x-2)(x+2)(x^2 + 4)}$$ is not equivalent, numerator factors differ \(\times\)
- c. $$\lim_{x \to 2} \frac{x^2 + 2x - 8}{x^4 - 16} = -\frac{3}{16}$$ incorrect sign \(\times\)
- d. $$\lim_{x \to 2} \frac{(x+4)(x-2)}{(x^2 - 4)(x^2 + 4)}$$ denominator expands to same as original denominator as $(x^2-4)=(x-2)(x+2)$, so this is equivalent \(\checkmark\)
- e. $$\lim_{x \to 2} \frac{(x+4)(x-2)}{(x-2)(x+2)(x^2 + 4)}$$ canceling $(x-2)$ yields same as a, so equivalent \(\checkmark\)
- f. $$\lim_{x \to 2} \frac{x^2 + 2x - 8}{x^4 - 16} = \frac{3}{16}$$ correct value \(\checkmark\)
- g. $$\lim_{x \to 2} \frac{x-4}{(x-2)(x^2 + 4)}$$ numerator differs, not equivalent \(\times\)
Final answers: a, d, e, f are true/equivalent.