Can’t get a start on solving a first order differential equation

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SUMMARY

The discussion focuses on solving a first-order, non-linear differential equation represented by the equation 3x²y + 8xy² + (x³ + 8x²y + 12y²)dy/dx = 0, with the initial condition y(2) = 1. The user attempted to apply separation of variables and check for exactness but encountered difficulties in isolating variables. The community suggested that the user likely miscalculated the derivatives M_y and N_x, as they are equal, indicating that the equation is indeed exact. The next step involves correctly applying integrating factors to find the general solution.

PREREQUISITES
  • Understanding of first-order differential equations
  • Familiarity with exact equations and the condition ∂M/∂y = ∂N/∂x
  • Knowledge of integrating factors and their application
  • Basic algebraic manipulation skills for differential equations
NEXT STEPS
  • Review the method for finding integrating factors in non-exact differential equations
  • Practice solving exact differential equations using the condition ∂M/∂y = ∂N/∂x
  • Explore techniques for separating variables in first-order differential equations
  • Study the implications of initial conditions on the solutions of differential equations
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Students studying differential equations, educators teaching calculus, and anyone seeking to improve their problem-solving skills in mathematical analysis.

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Homework Statement


Am looking at a first order, non linear differential equation. I want to solve for a general solution and will have to find a constant with given parameters. Equation: 3x2y+8xy2+[itex]([/itex]x3+8x2y+12y2[itex])[/itex][itex]dy/dx[/itex]=0 Parameters: y(2)=1

Homework Equations


[itex]∂M/∂y[/itex]=[itex]∂N/∂x[/itex] (Exactness) & [itex](My-Nx)/N[/itex] (integrating factors)

The Attempt at a Solution


I have tried to use separation of variable with no avail. When I try to separate them I can’t get it into terms of just x or just terms of y. I have tested for exactness and it failed, so I moved to the next step of integrating factors. After trying to solve for integrating factors I still cannot get function of x alone or y alone. When solveing for the equation listed in “Relevant equations” I get:((6xy+8y2-(24y+8x2))/(3x2y+8xy2).

Have tried intergrating factors both ways and still can't get a function of x or y alone. Can someone point in the right direction to starting this problem. I am swinging the bat but missing the ball b/c I don't see it. Thank you
 
Last edited by a moderator:
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You must have computed [itex]M_{y}[/itex] and/or [itex]N_{x}[/itex] incorrectly, because they are equal.
 
Last edited:

Homework Statement


Am looking at a first order, non linear differential equation. I want to solve for a general solution and will have to find a constant with given parameters. Equation: 3x2y+8xy2+[itex]([/itex]x3+8x2y+12y2[itex])[/itex][itex]dy/dx[/itex]=0 Parameters: y(2)=1

Homework Equations


[itex]∂M/∂y[/itex]=[itex]∂N/∂x[/itex] (Exactness) & [itex](My-Nx)/N[/itex] (integrating factors)

The Attempt at a Solution


I have tried to use separation of variable with no avail. When I try to separate them I can’t get it into terms of just x or just terms of y. I have tested for exactness and it failed, so I moved to the next step of integrating factors. After trying to solve for integrating factors I still cannot get function of x alone or y alone. When solveing for the equation listed in “Relevant equations” I get:((6xy+8y2-(24y+8x2))/(3x2y+8xy2).
6xy+ 8y is My but 24y+ 8x2 is Ny, not Nx.

Have tried intergrating factors both ways and still can't get a function of x or y alone. Can someone point in the right direction to starting this problem. I am swinging the bat but missing the ball b/c I don't see it. Thank you
 

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