Solving Differential Equations: Integrating (y+1)^2/y dy = x^2 ln x dx

basty
Messages
94
Reaction score
0
Thread was originally posted in a technical section, so does not include the template
I have differential equations problem, the problem is:

##\frac{(y+1)^2}{y} dy = x^2 \ln x \ dx##

Integrating both sides will yield:

##\frac{1}{2} y^2 + 2y + \ln y = \ln x \ . \frac{1}{3}x^3 - \frac{1}{9} x^3 + c##

Is this the final solution?

If not, what is the final solution?
 
Physics news on Phys.org
basty said:
I have differential equations problem, the problem is:

##\frac{(y+1)^2}{y} dy = x^2 \ln x \ dx##

Integrating both sides will yield:

##\frac{1}{2} y^2 + 2y + \ln y = \ln x \ . \frac{1}{3}x^3 - \frac{1}{9} x^3 + c##

Is this the final solution?

If not, what is the final solution?
Assuming your work is correct (I didn't check), what you got looks fine. You can check for yourself by differentiating both sides with respect to x. If what you ended with is correct, you should be able to get back to the equation at the beginning of your post.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
Back
Top