2. Evaluate each of the following limits (a) \( \lim _{x \rightarrow 2} \frac{x^{2}-4}{x-2} \) (b) \( \lim _{x \rightarrow 0} \frac{(x+4)^{2}-16}{x} \) (c) \( \lim _{x \rightarrow 3} \frac{x^{3}-9 x}{3 x^{2}-6 x-9} \) 3. Evaluate each of the following limits (a) \( \lim _{x \rightarrow 0} \frac{\sqrt{x+1}-1}{x} \) (b) \( \lim _{x \rightarrow 2} \frac{\sqrt{x+2}-2}{x-2} \) (c) \( \lim _{x \rightarrow 1} \frac{\sqrt{x+3}-2}{x-1} \)
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To solve the limits provided, let's break down each one step by step. 2. (a) \( \lim _{x \rightarrow 2} \frac{x^{2}-4}{x-2} \) Here, both the numerator and denominator approach zero as \( x \) approaches 2, leading us to apply L'Hôpital's rule or factor the expression. Factoring gives us: \[ \frac{(x-2)(x+2)}{x-2} \] Canceling \( x-2 \) (provided \( x \neq 2 \)), we get: \[ \lim_{x \rightarrow 2} (x + 2) = 4. \] (b) \( \lim _{x \rightarrow 0} \frac{(x+4)^{2}-16}{x} \) Substituting \( x = 0 \) gives an indeterminate form \( \frac{0}{0} \). We can expand the numerator: \[ (x+4)^{2} - 16 = x^{2} + 8x + 16 - 16 = x^{2} + 8x. \] Thus, \[ \frac{x^{2} + 8x}{x} = x + 8. \] Taking the limit: \[ \lim_{x \rightarrow 0} (x + 8) = 8. \] (c) \( \lim _{x \rightarrow 3} \frac{x^{3}-9 x}{3 x^{2}-6 x-9} \) Evaluating directly leads to: \[ \frac{0}{0} \] Applying L'Hôpital's rule: The derivative of the numerator \( 3x^2 - 9 \) and of the denominator \( 6x - 6 \): \[ \lim_{x \rightarrow 3} \frac{3x^2 - 9}{6x - 6} = \frac{27 - 9}{18 - 6} = \frac{18}{12} = \frac{3}{2}. \] 3. (a) \( \lim _{x \rightarrow 0} \frac{\sqrt{x+1}-1}{x} \) This again leads to \( \frac{0}{0} \). We can rationalize the numerator: \[ \frac{(\sqrt{x+1}-1)(\sqrt{x+1}+1)}{x(\sqrt{x+1}+1)} = \frac{x}{x(\sqrt{x+1}+1)} = \frac{1}{\sqrt{x+1}+1}. \] Evaluating the limit: \[ \lim_{x \rightarrow 0} \frac{1}{\sqrt{1}+1} = \frac{1}{2}. \] (b) \( \lim _{x \rightarrow 2} \frac{\sqrt{x+2}-2}{x-2} \) This limit also gives \( \frac{0}{0} \). Rationalizing the numerator yields: \[ \frac{(\sqrt{x+2}-2)(\sqrt{x+2}+2)}{(x-2)(\sqrt{x+2}+2)} = \frac{x-2}{(x-2)(\sqrt{x+2}+2)} = \frac{1}{\sqrt{x+2}+2}. \] Taking the limit, we find: \[ \lim_{x \rightarrow 2} \frac{1}{\sqrt{4}+2} = \frac{1}{4}. \] (c) \( \lim _{x \rightarrow 1} \frac{\sqrt{x+3}-2}{x-1} \) We get \( \frac{0}{0} \) again: Rationalizing: \[ \frac{(\sqrt{x+3}-2)(\sqrt{x+3}+2)}{(x-1)(\sqrt{x+3}+2)} = \frac{x+3-4}{(x-1)(\sqrt{x+3}+2)} = \frac{x-1}{(x-1)(\sqrt{x+3}+2)} = \frac{1}{\sqrt{x+3}+2}. \] Taking the limit: \[ \lim_{x \rightarrow 1} \frac{1}{\sqrt{4}+2} = \frac{1}{4}. \]
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