Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 2h 22m
4. Applications of Derivatives
Implicit Differentiation
Problem 70c
Textbook Question
The following equations implicitly define one or more functions.
c. Use the functions found in part (b) to graph the given equation.
y² = x²(4 − x) / 4 + x (right strophoid)

1
Identify the given implicit equation: \( y^2 = \frac{x^2(4 - x)}{4 + x} \). This is known as a right strophoid.
To graph the equation, first solve for \( y \) in terms of \( x \). This involves taking the square root of both sides: \( y = \pm \sqrt{\frac{x^2(4 - x)}{4 + x}} \).
Analyze the domain of the function. The expression under the square root, \( \frac{x^2(4 - x)}{4 + x} \), must be non-negative. Determine the values of \( x \) for which this is true.
Consider the behavior of the function as \( x \) approaches the critical points, such as where the denominator \( 4 + x = 0 \) or where the expression under the square root changes sign.
Plot the function using the derived expressions for \( y \) and the determined domain. Pay attention to symmetry and any asymptotic behavior to accurately represent the right strophoid.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Implicit Functions
Implicit functions are defined by equations where the dependent and independent variables are not isolated on one side. In the context of calculus, understanding how to derive and manipulate these functions is crucial for analyzing their behavior and graphing them. For example, the equation y² = x²(4 − x) / 4 + x defines y implicitly in terms of x.
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Graphing Techniques
Graphing techniques involve methods for visually representing mathematical functions and equations. This includes understanding the shape, intercepts, and asymptotic behavior of the graph. For the given equation, one must identify key points and the overall structure of the right strophoid to accurately depict it on a coordinate plane.
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Strophoid Curves
Strophoid curves are a family of curves defined by specific mathematical properties, often related to the geometry of circles and lines. The right strophoid, in particular, has unique characteristics that can be derived from its defining equation. Recognizing these properties helps in understanding the shape and behavior of the graph produced by the equation y² = x²(4 − x) / 4 + x.
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