Solving the Differential Equation

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SUMMARY

The discussion focuses on solving the differential equation dy/dx = x*y*sin(x) / (y+1). The user applies separation of variables, transforming the equation into (y+1)/y*dy = x*sin(x)*dx, and integrates to obtain y + ln(y) = -x*cos(x) + sin(x). However, the user encounters difficulty in explicitly solving for y. A key insight is that while an explicit solution for y may not be achievable, the integration process is valid, though the absence of an arbitrary constant '+C' is noted as a missing element.

PREREQUISITES
  • Understanding of differential equations and separation of variables
  • Familiarity with integration techniques, particularly for functions involving trigonometric identities
  • Knowledge of logarithmic functions and their properties
  • Basic concepts of arbitrary constants in solutions of differential equations
NEXT STEPS
  • Study the method of separation of variables in greater depth
  • Explore integration techniques for trigonometric functions, specifically integration by parts
  • Learn about implicit solutions of differential equations and their applications
  • Investigate the role of arbitrary constants in differential equations and their significance
USEFUL FOR

Students and professionals in mathematics, particularly those studying differential equations, as well as educators seeking to enhance their understanding of integration techniques and implicit solutions.

Manni
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I'm given the differential dy/dx = x*y*sinx / (y+1) and I need to find its solution.

I apply the following steps,

(y+1)/y*dy = x*sinx*dx

1 + 1/y*dy = x*sinx*dx

∫ 1 + 1/y*dy = ∫ x*sinx*dx

...skipping a few steps for convenience I get the equation

y + lny = -x*cosx + sinx

My problem now is that I don't know how do I solve for y.
 
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Manni said:
I'm given the differential dy/dx = x*y*sinx / (y+1) and I need to find its solution.

I apply the following steps,

(y+1)/y*dy = x*sinx*dx

1 + 1/y*dy = x*sinx*dx

∫ 1 + 1/y*dy = ∫ x*sinx*dx

...skipping a few steps for convenience I get the equation

y + lny = -x*cosx + sinx

My problem now is that I don't know how do I solve for y.

You can't solve nicely for y. That's often the case. But you've gotten rid of the derivatives, that should be enough. I do miss seeing an arbitrary constant (a '+C') somewhere in your solution.
 

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