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Ch. 3 - Derivatives
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Not the one you use?Change textbook
Chapter 3, Problem 44

Find by implicit differentiation.
x² + xy + y² - 5x = 2

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1
Start by differentiating both sides of the equation with respect to x. Remember that y is a function of x, so when differentiating terms involving y, use implicit differentiation.
Differentiate the term x² with respect to x, which gives 2x.
For the term xy, apply the product rule: differentiate x to get 1, multiply by y, then differentiate y with respect to x (dy/dx) and multiply by x. This results in y + x(dy/dx).
Differentiate y² with respect to x using the chain rule: 2y(dy/dx).
Differentiate the term -5x with respect to x, which gives -5. Set the derivative of the right side, which is a constant 2, to 0. Combine all these results to form the equation: 2x + y + x(dy/dx) + 2y(dy/dx) - 5 = 0.

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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 variable is not isolated on one side. Instead of solving for y explicitly, we differentiate both sides of the equation with respect to x, treating y as a function of x. This allows us to find dy/dx without needing to express y in terms of x.
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Chain Rule

The chain rule is a fundamental principle in calculus that allows us to differentiate composite functions. When applying implicit differentiation, we often encounter terms involving y, which requires us to use the chain rule to differentiate these terms correctly. For example, when differentiating y², we apply the chain rule to get 2y(dy/dx).
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Collecting Like Terms

Collecting like terms is a crucial step in simplifying equations after differentiation. After applying implicit differentiation, we often end up with an equation that contains multiple terms involving dy/dx. By rearranging and combining these terms, we can isolate dy/dx, making it easier to solve for the derivative and understand the relationship between x and y.
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