Graduate How to Solve This Differential Equation Analytically?

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The discussion centers on solving the differential equation $$\frac{2 y''}{y'} - \frac{y'}{y} = \frac{x'}{x}$$ analytically, where y and x are functions of t. A key hint provided is the transformation of terms into logarithmic derivatives, specifically $$\frac{2y''}{y'}=2\log\left(y'\right)',\quad\frac{y'}{y}=\log\left(y\right)',\quad\frac{x'}{x}=\log\left(x\right)'.$$ This approach suggests a method to simplify the equation for easier analysis. The conversation highlights the importance of recognizing patterns in differential equations to facilitate solutions. Overall, the thread emphasizes analytical techniques for tackling complex differential equations.
SantiagoCR
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calculate integral of a differential equation
Hello,

can someone help me to solve the following differential equation analitically:

$$\frac{2 y''}{y'} - \frac{y'}{y} = \frac{x'}{x}$$

where ##y = y(t)## and ##x = x(t)##

br

Santiago
 
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Hint: $$\frac{2y''}{y'}=2\log\left(y'\right)',\quad\frac{y'}{y}=\log\left(y\right)',\quad\frac{x'}{x}=\log\left(x\right)'$$
 
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Likes Kumail Haider, SantiagoCR, Frabjous and 1 other person
renormalize said:
Hint: $$\frac{2y''}{y'}=2\log\left(y'\right)',\quad\frac{y'}{y}=\log\left(y\right)',\quad\frac{x'}{x}=\log\left(x\right)'$$
cool, thank you very much!
 
There are probably loads of proofs of this online, but I do not want to cheat. Here is my attempt: Convexity says that $$f(\lambda a + (1-\lambda)b) \leq \lambda f(a) + (1-\lambda) f(b)$$ $$f(b + \lambda(a-b)) \leq f(b) + \lambda (f(a) - f(b))$$ We know from the intermediate value theorem that there exists a ##c \in (b,a)## such that $$\frac{f(a) - f(b)}{a-b} = f'(c).$$ Hence $$f(b + \lambda(a-b)) \leq f(b) + \lambda (a - b) f'(c))$$ $$\frac{f(b + \lambda(a-b)) - f(b)}{\lambda(a-b)}...

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