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diff equations

PostPosted: Tue Mar 11, 2008 10:39 pm
by pkciit
sin-1dy/dx =x+y
it's sin inverse don't get confused
plz give sol to the above :?:

Re: diff equations

PostPosted: Wed Mar 12, 2008 1:02 am
by kauser
sin-1dy/dx=x+y

dy/dx=sin(x+y)

dy=(sinxcosy+sinycosx)dx
integrating both sides

y= /sinxcosydx +/sinycosxdx

y= -cosycosx +sinysinx + C

/ is the integral sign :D

Re: diff equations

PostPosted: Wed Mar 12, 2008 4:10 pm
by kauser
the previous method is applicable if the question had been sin-1 (dy/dx)=x+a
(replacing all ys on the RHS by a)

Re: diff equations

PostPosted: Wed Mar 12, 2008 4:14 pm
by kauser
sin-1 (dy/dx)= x+y

dy/dx= sin(x+y).........1

z = x+y
dz/dx = 1+ dy/dx

dy/dx = dz/dx- 1

from 1

sinz = dz/dx-1

sinz+1= dz/dx

dz/(sinz+1) = dx

integrating both sides
..............

tanz - sec z = x+c

tan(x+y) - sec(x+y) = x+ c is the rqrd diff eqn

Re: diff equations

PostPosted: Wed Mar 12, 2008 9:19 pm
by pkciit
i had solved all the que's of diff equ but i was really not able to solve this
so thanks a lot buddy !!!!!!!!!!!!!! :lol: :lol: :lol:

Re: diff equations

PostPosted: Wed Mar 12, 2008 11:21 pm
by kauser
can any body pls give me the solutions.....atleast the starting for miscellaneous diff eqns Q.11, 12, 13, 14