Flag Integral Calculus> Please answer this question:: (e^x +1)ydy...
question mark

Please answer this question::(e^x +1)ydy - (y2+1)e^xdx = 0Given x=0 y=0

Aniket debnath , 5 Years ago
Grade 11
anser 4 Answers
Arun

Last Activity: 5 Years ago

Dear student
 
It can be written as 
 
y dy/(y^2 +1) = e^x dx /(e^x + 1)
 
Now I think you can do.
 
If you find any difficulty, please feel free to ask me again.

Aniket debnath

Last Activity: 5 Years ago

Please sir do the full solution
I have done 70% of the problem but can't go further please help.......

Samyak Jain

Last Activity: 5 Years ago

(ex + 1)ydy – (y2 + 1)exdx = 0
\Rightarrow ydy/(y2 + 1) = ex dx /(ex + 1)
2ydy/(y2 + 1) = 2ex dx /(ex + 1)
Now if  y2 + 1 = t, then differentiating both sides we get 2ydy = dt
and similarly ex + 1 = u, then ex dx = du
\therefore dt / t = 2 du / u .  Integratin both sides, we get
   ln(t)  =  2 ln(u)  +  lnc , where I’ve taken lnc as constant of integration and ln(t) means loge(t).
  ln(t) – 2 ln(u)  =  lnc  i.e. ln(t) – ln(u)2  =  lnc  or  ln(t/u2) = lnc
\Rightarrow t/u2 = c             [using rules of logarithm]
Substitute t as y2 + 1 and u as ex + 1 to get
(y2 + 1)/(ex + 1)2 = c      [You can rearrange the result to get the desired answer.]

Samyak Jain

Last Activity: 5 Years ago

Apply the condition : x = 0, y = 0 to get constant c
(y2 + 1)/(ex + 1)2 = c  
(02 + 1) / (e0 + 1)2 = c  =  1/(2)2 = 1/4
(y2 + 1) / (ex + 1)2  = 1/4 
i.e.   4(y2 + 1)  =  (ex + 1)2  

Provide a better Answer & Earn Cool Goodies

Enter text here...
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free

Enter text here...