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Mathematics 26 Online
OpenStudy (anonymous):

s

OpenStudy (anonymous):

@lgbasallote @EulerGroupie

OpenStudy (lgbasallote):

ok..i admit it...this is a good one

OpenStudy (lgbasallote):

im getting a tingly feeling something's wrong in this question =_=

OpenStudy (anonymous):

Haha, I dont think so..

OpenStudy (anonymous):

you'd need to change the variable , use \[\frac{y}{x} = t\]differentiate this with respect to x and change the equation so that all y/x is replaced everywhere by t, also in the square root part use \[x^2-y^2=(x+y)(x-y)\]

OpenStudy (lgbasallote):

lol nice. didnt see that =))

OpenStudy (lgbasallote):

but dy/dx changes too wont it?

OpenStudy (anonymous):

dy/dx = t + sqrt( 1-t^2)

OpenStudy (anonymous):

i think you do something to the dy/dx side dont know what thouhg

OpenStudy (anonymous):

\[\frac{y}{x}= t\]So,\[y= tx\]\[\frac{dy}{dx}=\frac{dt}{dx} +1\]

OpenStudy (anonymous):

you have to do product rule there

OpenStudy (anonymous):

so you would get t + x(dt/dx)

OpenStudy (anonymous):

Sorry, made a typo in the previous post\[\frac{dy}{dx} =\frac{dt}{dx} +t\] so the new equation becomes \[\frac{dt}{dx} +t = t+\sqrt{1-t^2}\]simplify and it reduces to form you'd be able to solve

OpenStudy (anonymous):

dt/dx =sqrt(1-t^2) then what?

OpenStudy (anonymous):

wait there hsould be an x in front of the dy/dx xdt/dx =sqrt(1-t^2)

OpenStudy (anonymous):

then you move the dt and dx's to the right side and integrate to get sin(t)^-1 +c = ln(x) + c. right?

OpenStudy (anonymous):

\[\frac{dt}{\sqrt{1-t^2}} =dx\]integrate both sides, you'd get \[sin^{-1}t= x +C\] now plug \[\frac{y}{x}=t\]\[Sin^{-1}\frac{y}{x} = x+C\] Use, y(1)=0\[Sin^{-1}0= 1+C\]hence, C= -1, plug this back into\[Sin^{-1}\frac{y}{x} = x+C\]\[Sin^{-1}\frac{y}{x} = x-1\]So we get, \[y = x Sin(x-1)\] this is the particular solution of the given differential equation.

OpenStudy (anonymous):

alright thanks

OpenStudy (anonymous):

You are welcome, it was fun. Good day.

OpenStudy (anonymous):

wait quick question where did the x go

OpenStudy (anonymous):

Becuase you have to do the product rule to get t + x(dt/dx)

OpenStudy (anonymous):

I am having that issue too. It gave me a natural log down the road.

OpenStudy (anonymous):

yeah same. do you think he made that mistake?

OpenStudy (anonymous):

Yeah, I finally found my book. That is how the substitution usually goes. I am scanning my work... brb

OpenStudy (anonymous):

Alright. Thanks man

hartnn (hartnn):

rhs=(1/x)dx which leads to ln x +c instead of x+c

OpenStudy (anonymous):

OpenStudy (anonymous):

Yeah I got the same stuff @EulerGroupie. @hartnn what is rhs

OpenStudy (anonymous):

right hand side

OpenStudy (anonymous):

oh. so we got it right?

hartnn (hartnn):

your work is correct @EulerGroupie

OpenStudy (anonymous):

Thank you, couldn't have done it without @akitav though.

OpenStudy (anonymous):

thanks again for the help guy s

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