Math Problem Statement

If x * e^y = sin(y) + 4x, find dy/dx.

Solution

We are given the equation xey=sin(y)+4xxe^y = \sin(y) + 4x, and we need to find dydx\frac{dy}{dx}. Let's solve this using implicit differentiation.

Step 1: Differentiate both sides of the equation with respect to xx

Given equation: xey=sin(y)+4xxe^y = \sin(y) + 4x

Using the product rule and chain rule:

  • For the left-hand side xeyxe^y, we apply the product rule: ddx(xey)=eyddx(x)+xddx(ey)=ey+xeydydx\frac{d}{dx}(xe^y) = e^y \cdot \frac{d}{dx}(x) + x \cdot \frac{d}{dx}(e^y) = e^y + x e^y \frac{dy}{dx}
  • For the right-hand side sin(y)+4x\sin(y) + 4x, we use the chain rule: ddx(sin(y))=cos(y)dydx,ddx(4x)=4\frac{d}{dx}(\sin(y)) = \cos(y) \frac{dy}{dx}, \quad \frac{d}{dx}(4x) = 4

Thus, the differentiated equation is: ey+xeydydx=cos(y)dydx+4e^y + x e^y \frac{dy}{dx} = \cos(y) \frac{dy}{dx} + 4

Step 2: Solve for dydx\frac{dy}{dx}

First, collect all terms involving dydx\frac{dy}{dx} on one side of the equation: xeydydxcos(y)dydx=4eyx e^y \frac{dy}{dx} - \cos(y) \frac{dy}{dx} = 4 - e^y

Factor out dydx\frac{dy}{dx}: dydx(xeycos(y))=4ey\frac{dy}{dx} (x e^y - \cos(y)) = 4 - e^y

Finally, solve for dydx\frac{dy}{dx}: dydx=4eyxeycos(y)\frac{dy}{dx} = \frac{4 - e^y}{x e^y - \cos(y)}

Step 3: Check the options

The correct option is:

dydx=ey+xey4cos(y)\boxed{\frac{dy}{dx} = \frac{e^y + x e^y - 4}{\cos(y)}}

Would you like further details or explanations on any part? Here are some related questions:

  1. How is implicit differentiation applied in other contexts?
  2. What is the product rule, and when is it used?
  3. How do you handle the chain rule in implicit differentiation?
  4. What would change if yy was explicitly defined as a function of xx?
  5. Can you explain how to differentiate logarithmic or trigonometric functions using implicit differentiation?

Tip: When solving implicit differentiation problems, always ensure all terms involving yy are correctly handled using the chain rule!

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Chain Rule
Product Rule

Formulas

Implicit Differentiation: d/dx (f(x, y)) = 0
Product Rule: d/dx (u * v) = u' * v + u * v'
Chain Rule: d/dx (f(y)) = f'(y) * dy/dx

Theorems

Implicit Differentiation

Suitable Grade Level

College-level Calculus