Math Problem Statement

π‘₯𝑦′=3π‘¦βˆ’6π‘₯2

Solution

The given differential equation is:

xyβ€²=3yβˆ’6x2x y' = 3y - 6x^2

Step 1: Rearranging the equation

First, let's divide both sides by xx (assuming x≠0x \neq 0) to isolate y′y':

yβ€²=3yxβˆ’6xy' = \frac{3y}{x} - 6x

This is a first-order linear differential equation.

Step 2: Solving the equation

This equation is in the form yβ€²+P(x)y=Q(x)y' + P(x)y = Q(x), where:

  • P(x)=βˆ’3xP(x) = -\frac{3}{x}
  • Q(x)=βˆ’6xQ(x) = -6x

We can solve it using an integrating factor.

Step 3: Finding the integrating factor

The integrating factor is given by: ΞΌ(x)=e∫P(x)dx=eβˆ«βˆ’3xdx\mu(x) = e^{\int P(x) dx} = e^{\int -\frac{3}{x} dx}

ΞΌ(x)=eβˆ’3ln⁑∣x∣=xβˆ’3\mu(x) = e^{-3 \ln |x|} = x^{-3}

Step 4: Multiplying both sides by the integrating factor

Now, multiply both sides of the original equation by xβˆ’3x^{-3}:

xβˆ’3yβ€²+xβˆ’3β‹…3yx=xβˆ’3(βˆ’6x)x^{-3} y' + x^{-3} \cdot \frac{3y}{x} = x^{-3} (-6x)

Simplifying:

xβˆ’3yβ€²+3xβˆ’4y=βˆ’6xβˆ’2x^{-3} y' + 3x^{-4} y = -6x^{-2}

The left-hand side is now the derivative of xβˆ’3yx^{-3} y:

ddx(xβˆ’3y)=βˆ’6xβˆ’2\frac{d}{dx} (x^{-3} y) = -6x^{-2}

Step 5: Integrating both sides

Integrate both sides with respect to xx:

xβˆ’3y=βˆ«βˆ’6xβˆ’2dxx^{-3} y = \int -6x^{-2} dx

xβˆ’3y=6xβˆ’1+Cx^{-3} y = 6x^{-1} + C

Step 6: Solving for yy

Multiply both sides by x3x^3 to solve for yy:

y=6x2+Cx3y = 6x^2 + Cx^3

Final Solution:

y(x)=6x2+Cx3y(x) = 6x^2 + Cx^3 where CC is the constant of integration.

Would you like further details or have any questions?

Here are some related questions you can explore:

  1. How do you verify the solution of a differential equation?
  2. What is an integrating factor, and why is it used?
  3. Can all first-order linear differential equations be solved using integrating factors?
  4. How do initial conditions affect the solution of this type of differential equation?
  5. What are some practical applications of first-order differential equations?

Tip: When solving linear differential equations, identifying the correct integrating factor simplifies the process significantly.

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Math Problem Analysis

Mathematical Concepts

Differential Equations
First-order Linear Equations
Integrating Factor

Formulas

y' + P(x)y = Q(x)
Integrating factor: μ(x) = e^∫P(x) dx
Final solution: y(x) = 6x^2 + Cx^3

Theorems

Integrating Factor Method

Suitable Grade Level

Grades 11-12