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y'=2y / x

y(1)=2

2007-05-05 20:00:28 · 5 answers · asked by Anonymous in Science & Mathematics Mathematics

5 answers

dy/dx=2y/x
dy/y=2.dx/x
ln(y)=2ln(x)+ln(c)
y=c.x^2

y(1)=2
2=c.1
c=2

y=2x^2

2007-05-05 20:37:26 · answer #1 · answered by gudspeling 7 · 1 0

i'm assuming that your first equation has an blunders in it and your 2nd one is authentic. it is, the final equation is (x^2 + 3xy +y^2)dx - x^2 dy = 0 is the final assertion. it is homogeneous. enable y = v x, so dy = x dv + v dx. replace for v, removing y and dy everywhere. Then simplify your equation. Then it is going to likely be accessible to split variables. Separate them, combine and remedy for v and finally for y.

2016-12-28 14:49:54 · answer #2 · answered by digiambattist 3 · 0 0

dy/dx=2y/x
dy/y=2dx/x
Integrating both sides
lnlyl=2lnlxl+lnc
No harm made if I put
instead c=lnc
lnlyl=ln(cx^2)
y=cx^2
I ignore abs.value of y
because c can take
both possitive or negative
values,
For x=1-->y=2
-->c=2
Then y=2x^2

2007-05-05 20:37:21 · answer #3 · answered by katsaounisvagelis 5 · 1 0

dy/dx=2y/x
dy/y=2.dx/x
ln(y)=2ln(x)+ln(c)
y=c.x^2
but given, y(1)=2
2=c.1
c=2

y=2x^2

2007-05-07 20:42:12 · answer #4 · answered by PREM K 1 · 1 0

dy/dx = 2y / x
(1/2).∫ (1/y).dy = ∫ (1/x).dx
(1/2).log y = log x + C
(1/2).(log 2) = log1 + C
C = (1/2) log 2
(1/2) log y = log x + (1/2) log 2
log y = 2 log x + log 2
log y = log x² + log 2
y = 2x²

2007-05-05 20:46:27 · answer #5 · answered by Como 7 · 1 0

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