seperation of variables help

bsanghera · #1 $Old$ October 13th, 2009, 03:39 PM

use seperation of variables

y' = (t^2)*e^(y+2t)

i got the answer of y(t) = (t^3)/3-2t+c

but online it tells me its wrong =(
what am i doing wrong??

on another note i dont even know how to start this one:

Danny · #2 $Old$ October 13th, 2009, 04:23 PM

Quote:

Originally Posted by bsanghera $View Post$

use seperation of variables

y' = (t^2)*e^(y+2t)

i got the answer of y(t) = (t^3)/3-2t+c

but online it tells me its wrong =(

what am i doing wrong??

on another note i dont even know how to start this one:

Not sure how you got your answer but separating gives

$e^{-y}dy = t^2 e^{2t}dt$

For the second

$\frac{dy}{\cos^2 y} = \sec^2 y dy = \ln t \,dt$ .

bsanghera · #3 $Old$ October 13th, 2009, 11:13 PM

ok i got

tan y =1/t + C

from there i take the arctan(1/t + C)???
im really frustrated and am never to finish a problem off i hate this feeling =(
thank you for your patience with me

Danny · #4 $Old$ October 14th, 2009, 06:25 AM

Quote:

Originally Posted by bsanghera $View Post$

ok i got

tan y =1/t + C

from there i take the arctan(1/t + C)???
im really frustrated and am never to finish a problem off i hate this feeling =(
thank you for your patience with me

You'll need to integrate the right hand side. You differentiated.