Math Problem Statement

Write the function in the form y = f(u) and u = g(x). Then find dy/dx as a function of x. y = e^(8/9 * x)

Solution

We are tasked with finding dydx\frac{dy}{dx} for the function given in the image.

The function is:

y=e89xy = e^{\frac{8}{9}x}

Step 1: Identify y=f(u)y = f(u) and u=g(x)u = g(x)

To rewrite this function in the form y=f(u)y = f(u) and u=g(x)u = g(x), we can set:

u=89xu = \frac{8}{9}x

This means the function for yy becomes:

y=euy = e^u

Thus, we have y=f(u)y = f(u) where f(u)=euf(u) = e^u and u=g(x)u = g(x) where g(x)=89xg(x) = \frac{8}{9}x.

Step 2: Differentiate using the chain rule

We need to compute dydx\frac{dy}{dx}, and we'll use the chain rule:

dydx=dydududx\frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx}

  • dydu=ddu(eu)=eu\frac{dy}{du} = \frac{d}{du}(e^u) = e^u
  • dudx=ddx(89x)=89\frac{du}{dx} = \frac{d}{dx}\left(\frac{8}{9}x\right) = \frac{8}{9}

Step 3: Combine results

Now, substitute the expressions into the chain rule formula:

dydx=eu89\frac{dy}{dx} = e^u \cdot \frac{8}{9}

Substitute u=89xu = \frac{8}{9}x back into the equation:

dydx=e89x89\frac{dy}{dx} = e^{\frac{8}{9}x} \cdot \frac{8}{9}

Thus, the derivative of the function is:

dydx=89e89x\frac{dy}{dx} = \frac{8}{9}e^{\frac{8}{9}x}

Would you like further explanation or have any questions?

Related Questions:

  1. How do you apply the chain rule in more complex functions?
  2. What is the derivative of a natural exponential function in general?
  3. How can the chain rule be extended to higher-order derivatives?
  4. How do you apply implicit differentiation when functions are not explicitly written in terms of xx?
  5. What is the significance of exponential functions in growth and decay problems?

Tip: When applying the chain rule, always differentiate the outer function first and then multiply by the derivative of the inner function.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Chain Rule
Exponential Functions

Formulas

dy/dx = dy/du * du/dx
Derivative of e^x = e^x

Theorems

Chain Rule

Suitable Grade Level

Grades 10-12