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 3.8.58a
Textbook Question
58–59. Carry out the following steps.
a. Use implicit differentiation to find dy/dx.
xy^5/2+x^3/2y=12; (4, 1)

1
Start by differentiating both sides of the equation with respect to x. Remember that y is a function of x, so you'll need to use implicit differentiation. The equation is: \( xy^{\frac{5}{2}} + x^{\frac{3}{2}}y = 12 \).
Apply the product rule to the term \( xy^{\frac{5}{2}} \). The product rule states that \( \frac{d}{dx}[u \cdot v] = u'v + uv' \). Here, let \( u = x \) and \( v = y^{\frac{5}{2}} \). Differentiate each part: \( u' = 1 \) and \( v' = \frac{5}{2}y^{\frac{3}{2}} \cdot \frac{dy}{dx} \).
Differentiate the second term \( x^{\frac{3}{2}}y \) using the product rule again. Let \( u = x^{\frac{3}{2}} \) and \( v = y \). Differentiate each part: \( u' = \frac{3}{2}x^{\frac{1}{2}} \) and \( v' = \frac{dy}{dx} \).
Combine the results from the differentiation steps. You will have an equation involving \( \frac{dy}{dx} \). Collect all terms involving \( \frac{dy}{dx} \) on one side of the equation and factor out \( \frac{dy}{dx} \).
Solve for \( \frac{dy}{dx} \) by isolating it on one side of the equation. Substitute the point (4, 1) into the equation to find the specific value of \( \frac{dy}{dx} \) at that point.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Implicit Differentiation
Implicit differentiation is a technique used to differentiate equations where the dependent and independent variables are not isolated on one side. Instead of solving for y explicitly, we differentiate both sides of the equation with respect to x, applying the chain rule when necessary. This method is particularly useful for equations that are difficult or impossible to rearrange.
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Chain Rule
The chain rule is a fundamental principle in calculus that allows us to differentiate composite functions. It states that if a function y is defined as a function of u, which in turn is a function of x, then the derivative of y with respect to x can be found by multiplying the derivative of y with respect to u by the derivative of u with respect to x. This is essential in implicit differentiation when dealing with terms involving y.
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Evaluating Derivatives at a Point
After finding the derivative dy/dx using implicit differentiation, it is often necessary to evaluate this derivative at a specific point, such as (4, 1) in this case. This involves substituting the x and y values into the derived expression to find the slope of the tangent line at that point. This step is crucial for understanding the behavior of the function at specific coordinates.
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