3. A man 5 feet tall walks at a rate of 4 ft/sec directly away from a street light which is 20 feet above the street. At what rate is the length of his shadow changing? Is the length increasing or decreasing?

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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**3.** A man 5 feet tall walks at a rate of 4 ft/sec directly away from a streetlight which is 20 feet above the street. At what rate is the length of his shadow changing? Is the length increasing or decreasing?

**4.** A train, starting at 11 am, travels east at 45 mph. Another train starts at noon from the same point, traveling south at 60 mph. How fast are the trains separating at 3 pm?
Transcribed Image Text:**3.** A man 5 feet tall walks at a rate of 4 ft/sec directly away from a streetlight which is 20 feet above the street. At what rate is the length of his shadow changing? Is the length increasing or decreasing? **4.** A train, starting at 11 am, travels east at 45 mph. Another train starts at noon from the same point, traveling south at 60 mph. How fast are the trains separating at 3 pm?
**Transcription for Educational Website:**

---

**1. Find the derivatives of the following functions.**

*Hint: Use logarithmic differentiation (take the natural log of both sides to start), then use implicit differentiation and solve for \( \frac{dy}{dx} \). Substitute in as necessary to reach an answer that only contains the variable \( x \).*

a) \[ y = (x^2 - 1)^{\ln x} \]

b) \[ y = x^{\log_2 x} \]

---

**2. Problem:**

The radius of a right circular cylinder is increasing at a rate of 2 inches/min and the height is decreasing at a rate of 3 inches/min. At what rate is the volume changing when the radius is 8 inches and the height is 12 inches? Is the volume increasing or decreasing?
Transcribed Image Text:**Transcription for Educational Website:** --- **1. Find the derivatives of the following functions.** *Hint: Use logarithmic differentiation (take the natural log of both sides to start), then use implicit differentiation and solve for \( \frac{dy}{dx} \). Substitute in as necessary to reach an answer that only contains the variable \( x \).* a) \[ y = (x^2 - 1)^{\ln x} \] b) \[ y = x^{\log_2 x} \] --- **2. Problem:** The radius of a right circular cylinder is increasing at a rate of 2 inches/min and the height is decreasing at a rate of 3 inches/min. At what rate is the volume changing when the radius is 8 inches and the height is 12 inches? Is the volume increasing or decreasing?
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