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 70b
Textbook Question
The following equations implicitly define one or more functions.
b. Solve the given equation for y to identify the implicitly defined functions y=f₁(x), y = f₂(x), ….
y² = x²(4 − x) / 4 + x (right strophoid)

1
Start by isolating the term involving y on one side of the equation. The given equation is y² = x²(4 − x) / 4 + x. We need to solve for y, so we have y² = (x²(4 − x) / 4) + x.
To solve for y, take the square root of both sides of the equation. This gives us y = ±√((x²(4 − x) / 4) + x). Remember that taking the square root introduces both positive and negative solutions.
Now, express the solutions as functions of x. We have two functions: y = f₁(x) = √((x²(4 − x) / 4) + x) and y = f₂(x) = -√((x²(4 − x) / 4) + x).
Consider the domain of the functions. Since we are taking the square root, the expression inside the square root must be non-negative. Set up the inequality (x²(4 − x) / 4) + x ≥ 0 and solve for x to find the domain.
Verify the solutions by substituting back into the original equation to ensure they satisfy y² = x²(4 − x) / 4 + x. This step confirms that the functions y = f₁(x) and y = f₂(x) are correctly derived from the implicit equation.

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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 variable is not isolated on one side. In the context of calculus, these functions can often be expressed in terms of the independent variable through algebraic manipulation. Understanding how to manipulate these equations is crucial for identifying the functions they define.
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Algebraic Manipulation
Algebraic manipulation involves rearranging and simplifying equations to isolate variables. This skill is essential when solving for y in an implicit equation, as it allows one to express y explicitly in terms of x. Techniques such as factoring, expanding, and using the quadratic formula may be necessary to achieve this.
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Quadratic Equations
Quadratic equations are polynomial equations of the form ax² + bx + c = 0, where a, b, and c are constants. In the context of the given equation, recognizing that it can be rearranged into a quadratic form in terms of y is vital. Solutions to quadratic equations can yield multiple values for y, representing different branches of the implicitly defined function.
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