Understanding the Role of Constants in First Order Differential Equations

converting1
Messages
65
Reaction score
0
solve dy/dx = x(1-x)

I got y = (x^2)/2 - (x^3)/3 + C

however in the solutions they've gotten:

259y0kp.png


where did t come from?
 
Physics news on Phys.org
It came when they integrated dt on the right hand side, 2 steps above where you marked the solution.
 
It looks to me like there is a typo in the problem. y disappeared! I think they meant the derivative to be dx/dt, not dy/dx. Your solution to dy/dx=x(1-x) is correct.
 
Oh nice spot!
 
Dick said:
It looks to me like there is a typo in the problem. y disappeared! I think they meant the derivative to be dx/dt, not dy/dx. Your solution to dy/dx=x(1-x) is correct.

Yeah it definitely looks like the problem was supposed to be dx/dt
 
thanks guys
 
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