Math Problem Statement

(x^2 - yx^2) dy + (y^2 + xy^2) dx = 0; x^2 dy - (2xy + 3y) dx = 0.

Solution

The image contains two differential equations:

  1. (x2yx2)dy+(y2+xy2)dx=0(x^2 - yx^2) \, dy + (y^2 + xy^2) \, dx = 0
  2. x2dy(2xy+3y)dx=0x^2 \, dy - (2xy + 3y) \, dx = 0

Let’s analyze and solve these equations step by step.


1. Solving the First Equation:

(x2yx2)dy+(y2+xy2)dx=0(x^2 - yx^2) \, dy + (y^2 + xy^2) \, dx = 0

Simplification:

  • Factor terms where possible: x2(1y)dy+y2(1+x)dx=0x^2(1 - y) \, dy + y^2(1 + x) \, dx = 0

Identify as a homogeneous differential equation:

This equation can be analyzed for homogeneity since all terms involve xx and yy. Rewrite it in the form: dydx=y2(1+x)x2(1y).\frac{dy}{dx} = -\frac{y^2(1 + x)}{x^2(1 - y)}.

At this point, we can solve the equation using substitution methods for homogeneous functions.


2. Solving the Second Equation:

x2dy(2xy+3y)dx=0x^2 \, dy - (2xy + 3y) \, dx = 0

Rearrange into standard form:

dydx=2xy+3yx2.\frac{dy}{dx} = \frac{2xy + 3y}{x^2}.

Simplify:

Factor yy from the numerator: dydx=y(2x+3)x2.\frac{dy}{dx} = \frac{y(2x + 3)}{x^2}.

Use separation of variables:

dyy=(2x+3)x2dx.\frac{dy}{y} = \frac{(2x + 3)}{x^2} \, dx.

Separate and integrate both sides: 1ydy=2xx2dx+3x2dx.\int \frac{1}{y} \, dy = \int \frac{2x}{x^2} \, dx + \int \frac{3}{x^2} \, dx.

The left-hand side integrates to lny\ln |y|. The right-hand side simplifies as follows: 2xx2dx=21xdx=2lnx,\int \frac{2x}{x^2} \, dx = 2 \int \frac{1}{x} \, dx = 2 \ln |x|, 3x2dx=3x.\int \frac{3}{x^2} \, dx = -\frac{3}{x}.

Combining results: lny=2lnx3x+C,\ln |y| = 2 \ln |x| - \frac{3}{x} + C, where CC is the constant of integration.


Final Solution for the Second Equation:

Exponentiate both sides to isolate yy: y=Cx2e3/x,y = Cx^2 e^{-3/x}, where CC is an arbitrary constant.


Would you like me to solve the first equation in more detail or explain a particular step? Let me know!


Related Questions:

  1. How do you solve homogeneous differential equations step by step?
  2. What is the method of separation of variables in differential equations?
  3. How do you check if a first-order equation is exact?
  4. What are the properties of integrating factors in differential equations?
  5. How do you solve non-linear first-order differential equations?

Tip: For equations involving xx and yy, always simplify terms first to check if they are separable, homogeneous, or exact.

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Math Problem Analysis

Mathematical Concepts

Differential Equations
Homogeneous Equations
Separation of Variables

Formulas

dy/dx = -M/N for standard differential equation M dx + N dy = 0
Separation of variables: dy/y = f(x) dx
Integral of 1/y: ∫(1/y) dy = ln|y|
Integral of 1/x: ∫(1/x) dx = ln|x|

Theorems

Separation of Variables
Homogeneous Functions

Suitable Grade Level

Undergraduate Mathematics or Advanced High School Calculus