Math Problem Statement

x^2y''+3xy'+y=0, y=x^-1

Solution

You are dealing with a second-order linear differential equation:

x2y+3xy+y=0x^2 y'' + 3xy' + y = 0

The function y=x1y = x^{-1} is proposed as a solution, so we need to check whether this satisfies the equation.

Step-by-Step Verification:

  1. Find yy' and yy'' for y=x1y = x^{-1}:

    y=x1=1xy = x^{-1} = \frac{1}{x}

    y=ddx(x1)=x2y' = \frac{d}{dx} \left( x^{-1} \right) = -x^{-2}

    y=ddx(x2)=2x3y'' = \frac{d}{dx} \left( -x^{-2} \right) = 2x^{-3}

  2. Substitute yy, yy', and yy'' into the given equation:

    x2y+3xy+y=0x^2 y'' + 3xy' + y = 0

    Substituting the values of y=x1y = x^{-1}, y=x2y' = -x^{-2}, and y=2x3y'' = 2x^{-3}:

    x2(2x3)+3x(x2)+x1=0x^2 (2x^{-3}) + 3x (-x^{-2}) + x^{-1} = 0

  3. Simplify each term:

    x2(2x3)=2x1x^2 (2x^{-3}) = 2x^{-1}

    3x(x2)=3x13x (-x^{-2}) = -3x^{-1}

    x1=x1x^{-1} = x^{-1}

  4. Combine all terms:

    2x13x1+x1=(23+1)x1=02x^{-1} - 3x^{-1} + x^{-1} = (2 - 3 + 1) x^{-1} = 0

    The equation simplifies to 0=00 = 0, which is true.

Conclusion:

The function y=x1y = x^{-1} satisfies the given differential equation.

Would you like more details or have any questions?


Here are 5 related questions to deepen your understanding:

  1. What is the general solution to a second-order linear differential equation?
  2. Can this equation have other solutions besides y=x1y = x^{-1}?
  3. How would the solution change if there was a non-homogeneous term (e.g., y=x1+sin(x)y = x^{-1} + \sin(x))?
  4. How do you solve second-order differential equations using the method of undetermined coefficients?
  5. How would you apply variation of parameters to solve such equations?

Tip: For verifying solutions to differential equations, always compute the derivatives carefully and substitute them back into the original equation for simplification.

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Math Problem Analysis

Mathematical Concepts

Differential Equations
Second-Order Linear Differential Equations
Homogeneous Equations
Verification of Solutions

Formulas

x^2 y'' + 3xy' + y = 0
y = x^{-1}
y' = -x^{-2}
y'' = 2x^{-3}

Theorems

Theory of Linear Homogeneous Differential Equations
Solution Verification for Differential Equations

Suitable Grade Level

Undergraduate - Calculus II or Differential Equations