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Tuesday, April 21, 2015

Separation of Variables - Arbitrary Constant, 7

Category: Differential Equations

"Published in Vacaville, California, USA"

Find the particular solution for


when x = 2; y = 3.

Solution:

Consider the given equation above   


Express y' as dy/dx as follows



By separation of variables, transfer x and dx to the right side of the equation and 1 + y² to the left side of the equation as follows 



Integrate on both sides of the equation, we have





Take the inverse natural logarithm on both sides of the equation, we have 




Substitute the values of x and y in order to solve for C as follows 






Therefore, the particular solution is 




Monday, April 20, 2015

Separation of Variables - Arbitrary Constant, 6

Category: Differential Equations

"Published in Newark, California, USA"

Find the particular solution for


when t = 0; r = r0.

Solution:

Consider the given equation above  


By separation of variables, transfer dt to the right side of the equation and r to the left side of the equation as follows



Integrate on both sides of the equation, we have  




Substitute the values of r and t in order to solve for C as follows




Therefore, the particular solution is





Take the inverse natural logarithm on both sides of the equation, we have




Sunday, April 19, 2015

Separation of Variables, 47

Category: Differential Equations

"Published in Newark, California, USA"

Find the general solution for


Solution:

Consider the given equation above 

  
Divide both sides of the equation by y ln y as follows




Integrate on both sides of the equation, we have  







Therefore, the general solution is