Wronskian Second Solution/Differential Equations

  • Thread starter Thread starter tracedinair
  • Start date Start date
  • Tags Tags
    Wronskian
tracedinair
Messages
47
Reaction score
0

Homework Statement



Given that Φ2 = Φ1 * ∫ e^(-∫a(x)dx)) / (Φ1)^2 dx

and Φ1 = cos(ln(x)), a = 1/x, solve for Φ2.

Homework Equations



The Attempt at a Solution



Φ2 = cos(ln(x)) * ∫ e^(-∫1/x dx)) / cos^(2)(ln(x)) dx

= cos(ln(x)) * ∫ e^(-ln(x)) / cos^(2)(ln(x)) dx

= cos(ln(x)) * - ∫ x / cos^(2)(ln(x)) dx

My problem begins here with trying to solve for that integral. I don't have the slightest idea where to begin, except maybe integration by parts.
 
Physics news on Phys.org
I believe you have expanded your brackets in the exponential wrong e^{-ln(x)} does not equal -x but rather e^{ln(x^{-1})} which is of course \frac{1}{x} in which case a simple u substitution will work
 
djeitnstine said:
I believe you have expanded your brackets in the exponential wrong e^{-ln(x)} does not equal -x but rather e^{ln(x^{-1})} which is of course \frac{1}{x} in which case a simple u substitution will work

Thanks for catching that mistake.
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
Back
Top