Ordinary Differential Equations

aaronfue
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Homework Statement



y = 2xy' + y(y')2; y2 = C1 (x + C1 /4)



2. The attempt at a solution

I thought that I could take the first equation and set it equal to zero. But the C1 in the second equation is throwing me off.

Am I supposed to set the second equal to C1?
 
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Are you saying that you want to show that y= \pm\sqrt{C_1(x+ \frac{C_1}{4})} satisfies [/itex]y= 2xy'+ y(y')^2[/itex]?

Just find the derivative of y and plug it into the equation.
 
HallsofIvy said:
Are you saying that you want to show that y= \pm\sqrt{C_1(x+ \frac{C_1}{4})} satisfies [/itex]y= 2xy'+ y(y')^2[/itex]?

Just find the derivative of y and plug it into the equation.

Sorry the second equation is y2, but I think I see what you are saying.
 
Yes, that's why I took the square root to get y.
 
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...
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