Limit Evaluation D32374
1. **Problem statement:**
Find the following limits:
(i) $$\lim_{x \to 3^-} \frac{x^3 - 12}{x - 3}$$
(ii) $$\lim_{x \to -2^-} \frac{x^3}{x + 2}$$
2. **Recall the limit definition and approach:**
When evaluating limits where direct substitution leads to an indeterminate form like $$\frac{0}{0}$$, we try to simplify the expression.
3. **Evaluate (i):**
Substitute $$x=3$$ directly:
$$\frac{3^3 - 12}{3 - 3} = \frac{27 - 12}{0} = \frac{15}{0}$$ which is undefined but not indeterminate.
Since denominator approaches 0, check the sign of numerator and denominator as $$x \to 3^-$$:
- Numerator near 3: $$x^3 - 12$$ at $$x=3$$ is 15 (positive).
- Denominator near 3 from left: $$x - 3$$ is slightly less than 0 (negative).
So the fraction approaches $$\frac{+}{-} = -\infty$$.
4. **Evaluate (ii):**
Substitute $$x = -2$$ directly:
$$\frac{(-2)^3}{-2 + 2} = \frac{-8}{0}$$ undefined.
Check signs as $$x \to -2^-$$:
- Numerator: $$x^3$$ near $$-2$$ is slightly less than $$-8$$ (negative).
- Denominator: $$x + 2$$ near $$-2$$ from left is slightly less than 0 (negative).
So the fraction approaches $$\frac{-}{-} = +\infty$$.
**Final answers:**
(i) $$\lim_{x \to 3^-} \frac{x^3 - 12}{x - 3} = -\infty$$
(ii) $$\lim_{x \to -2^-} \frac{x^3}{x + 2} = +\infty$$