Math Problem Statement

Given f(x, y) = x^2 + x^2y^3 - 2y^2. Evaluate fx, fy.

Solution

The problem presented is to evaluate the partial derivatives of the function f(x,y)=x2+x2y32y2f(x, y) = x^2 + x^2y^3 - 2y^2, with respect to xx and yy.

Let's compute the partial derivatives:

1. Partial derivative with respect to xx (fxf_x):

To find fxf_x, we differentiate f(x,y)=x2+x2y32y2f(x, y) = x^2 + x^2y^3 - 2y^2 with respect to xx, treating yy as a constant:

fx=x(x2+x2y32y2)f_x = \frac{\partial}{\partial x} \left( x^2 + x^2y^3 - 2y^2 \right)

Step by step:

  • The derivative of x2x^2 with respect to xx is 2x2x.
  • The derivative of x2y3x^2y^3 (where y3y^3 is treated as a constant) is 2xy32xy^3.
  • The derivative of 2y2-2y^2 with respect to xx is 00, since it doesn't depend on xx.

So, we have:

fx=2x+2xy3f_x = 2x + 2xy^3

2. Partial derivative with respect to yy (fyf_y):

To find fyf_y, we differentiate f(x,y)=x2+x2y32y2f(x, y) = x^2 + x^2y^3 - 2y^2 with respect to yy, treating xx as a constant:

fy=y(x2+x2y32y2)f_y = \frac{\partial}{\partial y} \left( x^2 + x^2y^3 - 2y^2 \right)

Step by step:

  • The derivative of x2x^2 with respect to yy is 00, since it doesn't depend on yy.
  • The derivative of x2y3x^2y^3 (where x2x^2 is treated as a constant) is 3x2y23x^2y^2.
  • The derivative of 2y2-2y^2 with respect to yy is 4y-4y.

So, we have:

fy=3x2y24yf_y = 3x^2y^2 - 4y

Final results:

  • fx=2x+2xy3f_x = 2x + 2xy^3
  • fy=3x2y24yf_y = 3x^2y^2 - 4y

Would you like more details or explanations?

Relative questions:

  1. What is the significance of partial derivatives in multivariable functions?
  2. How can we interpret fxf_x and fyf_y geometrically?
  3. What are the higher-order partial derivatives for this function?
  4. How do partial derivatives apply to optimization problems in calculus?
  5. What is the difference between a total derivative and a partial derivative?

Tip:

When finding partial derivatives, always treat all other variables as constants except for the one you're differentiating with respect to.

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Math Problem Analysis

Mathematical Concepts

Partial Derivatives
Multivariable Calculus

Formulas

Partial derivative with respect to x: fx = ∂f/∂x
Partial derivative with respect to y: fy = ∂f/∂y

Theorems

Chain Rule for Multivariable Functions

Suitable Grade Level

Grades 10-12