Chapter 23: Problem 7
Find \(d y / d x\) by differentiating implicitly. When applicable, express the result in terms of \(x\) and $y.$$3 x+2 y=5$$
Short Answer
Expert verified
\( \frac{dy}{dx} = -\frac{3}{2} \)
Step by step solution
01
Differentiate both sides of the equation with respect to x
The given equation is: \[ 3x + 2y = 5 \] Differentiate both sides with respect to \( x \): \[ \frac{d}{dx}(3x + 2y) = \frac{d}{dx}(5) \] Recall that the derivative of a constant is zero: \[ \frac{d}{dx}(5) = 0 \] Thus, we need to differentiate \( 3x + 2y \).
02
Apply the derivative
For \( 3x \), use the power rule: \[ \frac{d}{dx}(3x) = 3 \]For \( 2y \), apply the chain rule: \[ \frac{d}{dx}(2y) = 2 \cdot \frac{dy}{dx} \]So, the derivative of the left-hand side is:\[ 3 + 2 \frac{dy}{dx} \]
03
Set the derivative expression equal to the right-hand side
Set the derivative of the left side equal to the derivative of the right side:\[ 3 + 2 \frac{dy}{dx} = 0 \]
04
Solve for dy/dx
Subtract 3 from both sides to isolate the term involving \( \frac{dy}{dx} \):\[ 2 \frac{dy}{dx} = -3 \] Divide by 2 to solve for \( \frac{dy}{dx} \):\[ \frac{dy}{dx} = -\frac{3}{2} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Derivative with respect to x
When solving calculus problems involving implicit differentiation, it's essential to know how to take the derivative with respect to a specific variable like \( x \). This means you treat every other variable (such as \( y \)) as implicitly dependent on \( x \). For the equation \( 3x + 2y = 5 \), we differentiate each term separately.
- The term \( 3x \) is straightforward because it's directly in terms of \( x \).
- The term \( 2y \) requires more attention since \( y \) is not originally a function of \( x \).
Chain Rule
The chain rule is a key tool used in implicit differentiation. It helps us deal with derivatives when one function is nested inside another. With implicit differentiation, it's useful for terms where \( y \) depends on \( x \). When we differentiate such terms, we must account for this dependency by using the chain rule.When we differentiate \( 2y \), we apply the chain rule: - The derivative of \( y \) with respect to \( x \) is \( \frac{dy}{dx} \). - Thus, the derivative of \( 2y \) becomes \( 2 \cdot \frac{dy}{dx} \).
Using the chain rule ensures that we're capturing the hidden relationships between \( y \) and \( x \), which is crucial for accurate differentiation in implicit contexts.
Using the chain rule ensures that we're capturing the hidden relationships between \( y \) and \( x \), which is crucial for accurate differentiation in implicit contexts.
Power Rule
The power rule simplifies the process of differentiation when dealing with polynomial terms. For any term \( ax^n \), the derivative is \( anx^{n-1} \). In our exercise, the term \( 3x \) is effectively \( 3x^1 \), making its differentiation very straightforward.Applying the power rule: - For \( 3x \), the derivative with respect to \( x \) is simply \( 3 \), as \( n = 1 \) leads to \( 1 \times 3x^{1-1} = 3 \times x^0 = 3 \).This rule is the reason our calculations were so simple for this part of the problem, and it often makes differentiating polynomial terms intuitive and quick.
Solving for dy/dx
Once differentiation is complete, the next step involves solving for \( \frac{dy}{dx} \). We need to rearrange the equation to isolate this term. In the equation \( 3 + 2 \frac{dy}{dx} = 0 \), our goal is to solve for \( \frac{dy}{dx} \). The process involves:
- Subtracting 3 from both sides, resulting in \( 2 \frac{dy}{dx} = -3 \).
- Dividing both sides by 2 to isolate \( \frac{dy}{dx} \).