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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.8.3c

3. Which of the following functions grow faster than x² as x→∞? Which grow at the same rate as x²? Which grow slower?
c. √(x^4 + x^3)

Guida verificata passo dopo passo
1
Rewrite the function to better understand its growth rate. The function is \(\sqrt{x^4 + x^3}\). Since the square root is the same as raising to the power \(\frac{1}{2}\), rewrite it as \(\left(x^4 + x^3\right)^{\frac{1}{2}}\).
Factor out the highest power of \(x\) inside the parentheses to simplify the expression. The highest power inside is \(x^4\), so factor it out: \(\left(x^4\left(1 + \frac{1}{x}\right)\right)^{\frac{1}{2}}\).
Use the property of exponents to separate the factors: \(\left(x^4\right)^{\frac{1}{2}} \cdot \left(1 + \frac{1}{x}\right)^{\frac{1}{2}} = x^{4 \cdot \frac{1}{2}} \cdot \left(1 + \frac{1}{x}\right)^{\frac{1}{2}} = x^2 \cdot \left(1 + \frac{1}{x}\right)^{\frac{1}{2}}\).
Analyze the behavior of \(\left(1 + \frac{1}{x}\right)^{\frac{1}{2}}\) as \(x \to \infty\). Since \(\frac{1}{x} \to 0\), this term approaches \(1\).
Conclude that the function behaves like \(x^2\) times a term approaching \(1\), so its growth rate is asymptotically similar to \(x^2\). Therefore, it grows at the same rate as \(x^2\) as \(x \to \infty\).

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