Sunday, February 3, 2019

y' + ytanx = secx + cosx , y(0) = 1 Find the particular solution of the differential equation that satisfies the initial condition

Given y'+ytanx=secx+cosx
when the first order linear ordinary Differentian equation has the form of
y'+p(x)y=q(x)
then the general solution is ,
y(x)=((int e^(int p(x) dx) *q(x)) dx +c)/ e^(int p(x) dx)
so,
y'+ytanx=secx+cosx--------(1)
y'+p(x)y=q(x)---------(2)
on comparing both we get,
p(x) = tanx and q(x)=secx +cosx
so on solving with the above general solution we get:
y(x)=((int e^(int p(x) dx) *q(x)) dx +c)/e^(int p(x) dx)
=((int e^(int (tanx) dx) *(secx+cosx)) dx +c)/e^(int tanx dx)
first we shall solve
e^(int (tanx) dx)=e^(ln(secx))= secx     
so proceeding further, we get
y(x) =((int e^(int (tanx) dx) *(secx+cosx)) dx +c)/e^(int tanx dx)
=((int secx *(secx+cosx)) dx +c)/(secx )
=((int (sec^2 x+cosxsecx)) dx +c)/(secx )
= ((int (sec^2 x)dx +int 1 dx) +c)/secx
= (tanx+x +c)/secx
= sinx +(x+c)/secx
y(x) = sinx +(x+c)/secx
 
 
to find the particular solution of the differential equation we have y(0)=1
 
on substituting x=0 we get y=1 and so we can find the value of the c
y(0)= sin0+(0+c)/sec0 =0+0+c/1 = c
but y(0)=1
=> 1=c
=> c=1
so y=sinx+(x+1)/secx 

No comments:

Post a Comment

Summarize the major research findings of "Toward an experimental ecology of human development."

Based on findings of prior research, the author, Bronfenbrenner proposes that methods for natural observation research have been applied in ...