Math Problem Statement

Find y' if x^y = y^x.

Solution

The equation provided in the image is:

xy=yxx^y = y^x

We need to find yy' (the derivative of yy with respect to xx).

Steps to solve:

  1. Start by taking the natural logarithm of both sides to simplify the powers: ln(xy)=ln(yx)\ln(x^y) = \ln(y^x) Using logarithmic properties (ln(ab)=bln(a)\ln(a^b) = b \ln(a)): yln(x)=xln(y)y \ln(x) = x \ln(y)

  2. Differentiate both sides of this equation with respect to xx. Apply implicit differentiation:

    For the left-hand side yln(x)y \ln(x): ddx[yln(x)]=yln(x)+y1x\frac{d}{dx} [y \ln(x)] = y' \ln(x) + y \cdot \frac{1}{x}

    For the right-hand side xln(y)x \ln(y): ddx[xln(y)]=ln(y)+xyy\frac{d}{dx} [x \ln(y)] = \ln(y) + x \cdot \frac{y'}{y}

  3. Now set the two derivatives equal: yln(x)+yx=ln(y)+xyyy' \ln(x) + \frac{y}{x} = \ln(y) + \frac{x y'}{y}

  4. Collect terms involving yy' on one side: yln(x)xyy=ln(y)yxy' \ln(x) - \frac{x y'}{y} = \ln(y) - \frac{y}{x}

  5. Factor out yy' on the left-hand side: y(ln(x)xy)=ln(y)yxy' \left( \ln(x) - \frac{x}{y} \right) = \ln(y) - \frac{y}{x}

  6. Solve for yy': y=ln(y)yxln(x)xyy' = \frac{\ln(y) - \frac{y}{x}}{\ln(x) - \frac{x}{y}}

Thus, the derivative yy' is:

y=ln(y)yxln(x)xyy' = \frac{\ln(y) - \frac{y}{x}}{\ln(x) - \frac{x}{y}}

Would you like further clarification on any step or more details about logarithmic differentiation?

Here are 5 related questions you might explore:

  1. How do we handle logarithmic differentiation in other types of equations?
  2. What are the general rules for implicit differentiation?
  3. Can we apply this method to non-exponential equations?
  4. How does the product rule apply in implicit differentiation?
  5. What happens when x=yx = y in the original equation?

Tip: Always remember to apply the chain rule when differentiating functions involving products of variables!

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Logarithmic Differentiation
Exponential Functions

Formulas

ln(a^b) = b * ln(a)
Implicit differentiation: d/dx[f(y)] = f'(y) * dy/dx

Theorems

Chain Rule
Product Rule

Suitable Grade Level

Undergraduate Calculus or Advanced High School