Math Problem Statement

Find ∂f/∂x and ∂f/∂y for f(x)=2x^2-xy+xy^2.

Solution

Let's compute the partial derivatives of the given function f(x,y)=2x2xy+xy2f(x, y) = 2x^2 - xy + xy^2 with respect to xx and yy.

Partial Derivative with respect to xx:

To find fx\frac{\partial f}{\partial x}, we treat yy as a constant and differentiate each term of the function with respect to xx.

f(x,y)=2x2xy+xy2f(x, y) = 2x^2 - xy + xy^2

Differentiating term by term:

  1. x(2x2)=4x\frac{\partial}{\partial x}(2x^2) = 4x
  2. x(xy)=y\frac{\partial}{\partial x}(-xy) = -y (since yy is constant with respect to xx)
  3. x(xy2)=y2\frac{\partial}{\partial x}(xy^2) = y^2 (since y2y^2 is treated as constant with respect to xx)

Thus, the partial derivative with respect to xx is:

fx=4xy+y2\frac{\partial f}{\partial x} = 4x - y + y^2

Partial Derivative with respect to yy:

To find fy\frac{\partial f}{\partial y}, we treat xx as a constant and differentiate each term of the function with respect to yy.

  1. y(2x2)=0\frac{\partial}{\partial y}(2x^2) = 0 (since x2x^2 does not depend on yy)
  2. y(xy)=x\frac{\partial}{\partial y}(-xy) = -x
  3. y(xy2)=2xy\frac{\partial}{\partial y}(xy^2) = 2xy (using the power rule)

Thus, the partial derivative with respect to yy is:

fy=x+2xy\frac{\partial f}{\partial y} = -x + 2xy

Final Answer:

  • fx=4xy+y2\frac{\partial f}{\partial x} = 4x - y + y^2
  • fy=x+2xy\frac{\partial f}{\partial y} = -x + 2xy

Would you like to explore further details or have any questions about these derivatives?


Here are 5 related questions to expand your understanding:

  1. How do partial derivatives apply in multivariable optimization problems?
  2. What is the concept of mixed partial derivatives, and how are they computed?
  3. How do partial derivatives relate to the gradient of a function?
  4. What is the meaning of the total derivative in the context of multivariable functions?
  5. How can the chain rule be used with multivariable functions to compute derivatives?

Tip: Partial derivatives measure how a function changes as one variable changes while the others are held constant. This is important when working with functions of several variables!

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Math Problem Analysis

Mathematical Concepts

Partial Derivatives
Multivariable Functions
Differentiation

Formulas

∂f/∂x = 4x - y + y^2
∂f/∂y = -x + 2xy

Theorems

Power Rule
Constant Rule

Suitable Grade Level

Grades 11-12