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5. Show that \( \lim _{x \rightarrow 9} \sqrt{x}=3 \). 6. Evaluate the following limits using the Squeeze Theorem a) \( \lim _{x \rightarrow 0} x^{4} \sin \left(\frac{7}{x}\right)+5 \).

Ask by Stephens Clark. in South Africa
Mar 14,2025

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**5. Show that \( \lim_{x \rightarrow 9} \sqrt{x} = 3 \).** Since \( \sqrt{x} \) is continuous at \( x = 9 \), \[ \lim_{x \rightarrow 9} \sqrt{x} = \sqrt{9} = 3. \] --- **6a. Evaluate \( \lim_{x \rightarrow 0} \left( x^{4} \sin \left(\frac{7}{x}\right) + 5 \right) \) using the Squeeze Theorem.** Because \( \sin\left(\frac{7}{x}\right) \) is between -1 and 1, \[ -x^4 \leq x^4 \sin\left(\frac{7}{x}\right) \leq x^4. \] As \( x \rightarrow 0 \), both \( -x^4 \) and \( x^4 \) approach 0, so by the Squeeze Theorem, \[ \lim_{x \rightarrow 0} x^4 \sin\left(\frac{7}{x}\right) = 0. \] Adding 5, the limit is \[ \lim_{x \rightarrow 0} \left( x^{4} \sin\left(\frac{7}{x}\right) + 5 \right) = 5. \]

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To show that \( \lim _{x \rightarrow 9} \sqrt{x}=3 \), we can use the direct substitution method. As \( x \) approaches 9, substituting \( x = 9 \) into the square root gives \( \sqrt{9} = 3 \). Since this is a continuous function, the limit follows directly as \( x \) approaches 9. For the limit \( \lim _{x \rightarrow 0} x^{4} \sin \left(\frac{7}{x}\right) + 5 \), we can apply the Squeeze Theorem. We know that \( -1 \leq \sin \left(\frac{7}{x}\right) \leq 1 \), hence \( -x^4 \leq x^4 \sin \left(\frac{7}{x}\right) \leq x^4 \). As \( x \) approaches 0, both \( -x^4 \) and \( x^4 \) approach 0. Therefore, by the Squeeze Theorem, \( \lim _{x \rightarrow 0} x^{4} \sin \left(\frac{7}{x}\right) = 0 \). Adding 5 gives \( 5 \). Thus, the overall limit is \( 5 \).

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