Math Problem Statement

Using Chain rule, find ∂f/∂t | (t,w)=(1,1). f(x,y)=e^(xy^3) , x=t^2+w^2, y=tw^2.

Solution

To find ft(t,w)=(1,1)\frac{\partial f}{\partial t} \bigg|_{(t,w)=(1,1)} using the Chain Rule, let's follow these steps:

  1. Express ff in terms of tt and ww: f(x,y)=exy3f(x, y) = e^{xy^3} where x=t2+w2andy=tw2.x = t^2 + w^2 \quad \text{and} \quad y = tw^2.

  2. Compute the partial derivatives fx\frac{\partial f}{\partial x} and fy\frac{\partial f}{\partial y}: fx=ddx(exy3)=y3exy3,\frac{\partial f}{\partial x} = \frac{d}{dx}\left(e^{xy^3}\right) = y^3 e^{xy^3}, fy=ddy(exy3)=3xy2exy3.\frac{\partial f}{\partial y} = \frac{d}{dy}\left(e^{xy^3}\right) = 3xy^2 e^{xy^3}.

  3. Compute the partial derivatives xt\frac{\partial x}{\partial t} and yt\frac{\partial y}{\partial t}: xt=ddt(t2+w2)=2t,\frac{\partial x}{\partial t} = \frac{d}{dt}(t^2 + w^2) = 2t, yt=ddt(tw2)=w2.\frac{\partial y}{\partial t} = \frac{d}{dt}(tw^2) = w^2.

  4. Apply the Chain Rule: ft=fxxt+fyyt.\frac{\partial f}{\partial t} = \frac{\partial f}{\partial x} \frac{\partial x}{\partial t} + \frac{\partial f}{\partial y} \frac{\partial y}{\partial t}.

  5. Substitute the values of the partial derivatives and the expressions for ff, xx, and yy: ft=(y3exy3)(2t)+(3xy2exy3)(w2).\frac{\partial f}{\partial t} = (y^3 e^{xy^3}) (2t) + (3xy^2 e^{xy^3}) (w^2).

  6. Evaluate at t=1t = 1 and w=1w = 1: x=12+12=2,x = 1^2 + 1^2 = 2, y=112=1.y = 1 \cdot 1^2 = 1. Therefore, fx(t,w)=(1,1)=13e213=e2,\frac{\partial f}{\partial x} \bigg|_{(t,w)=(1,1)} = 1^3 e^{2 \cdot 1^3} = e^2, fy(t,w)=(1,1)=3212e213=6e2.\frac{\partial f}{\partial y} \bigg|_{(t,w)=(1,1)} = 3 \cdot 2 \cdot 1^2 e^{2 \cdot 1^3} = 6e^2. Also, xt(t,w)=(1,1)=21=2,\frac{\partial x}{\partial t} \bigg|_{(t,w)=(1,1)} = 2 \cdot 1 = 2, yt(t,w)=(1,1)=12=1.\frac{\partial y}{\partial t} \bigg|_{(t,w)=(1,1)} = 1^2 = 1.

  7. Combine all these values: ft(t,w)=(1,1)=(e2)(2)+(6e2)(1)=2e2+6e2=8e2.\frac{\partial f}{\partial t} \bigg|_{(t,w)=(1,1)} = (e^2)(2) + (6e^2)(1) = 2e^2 + 6e^2 = 8e^2.

So, ft(t,w)=(1,1)=8e2\frac{\partial f}{\partial t} \bigg|_{(t,w)=(1,1)} = 8e^2.

Would you like more details or have any questions?

Here are 5 more questions you can ask:

  1. How do you find the second derivative using the chain rule?
  2. Can you explain the product rule with an example?
  3. What is the integral of exye^{xy} with respect to xx?
  4. How do you solve differential equations using the chain rule?
  5. What is the gradient of a multivariable function?

Tip: Always break down complex problems into smaller parts to simplify the solution process.

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Math Problem Analysis

Mathematical Concepts

Chain Rule
Partial Derivatives
Exponential Functions

Formulas

Chain Rule for partial derivatives

Theorems

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Suitable Grade Level

Advanced Undergraduate