Subjects calculus

Limit X To Minus1 6Bd5B8

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1. **State the problem:** Find the limit \( \lim_{x \to -1} \frac{x^2 + x}{(x+1)^4} \). 2. **Recall the formula and rules:** When evaluating limits involving rational functions, if direct substitution leads to an indeterminate form like \( \frac{0}{0} \), factor and simplify the expression. 3. **Factor numerator:** \( x^2 + x = x(x+1) \). 4. **Rewrite the limit:** $$\lim_{x \to -1} \frac{x(x+1)}{(x+1)^4} = \lim_{x \to -1} \frac{x \cancel{(x+1)}}{\cancel{(x+1)} (x+1)^3} = \lim_{x \to -1} \frac{x}{(x+1)^3}$$ 5. **Evaluate the simplified limit:** Substitute \( x = -1 \): $$\frac{-1}{(0)^3} = \frac{-1}{0}$$ 6. **Interpretation:** Division by zero indicates the limit tends to infinity or negative infinity depending on the sign of the denominator near \( x = -1 \). 7. **Check the sign of denominator near \( x = -1 \):** - For \( x \to -1^+ \), \( (x+1)^3 > 0 \), so the fraction \( \frac{x}{(x+1)^3} \to -\infty \). - For \( x \to -1^- \), \( (x+1)^3 < 0 \), so the fraction \( \frac{x}{(x+1)^3} \to +\infty \). **Final answer:** The limit does not exist because the left and right limits are not equal: $$\lim_{x \to -1^-} \frac{x^2 + x}{(x+1)^4} = +\infty, \quad \lim_{x \to -1^+} \frac{x^2 + x}{(x+1)^4} = -\infty$$