1. ## some tricky eqn

so, my assignment is due in 4 hours, but i can't solve this eqn

dy/dt = -y^4 + 2y^3 + 63y^2

my TA told me to isolate the equation for -y^2, and that's what i got:

dy/dt = -y^2(y^2 - 2y - 63)
= -y^2(y - 9)(y + 7)

i have no clue to solve it...

2. Originally Posted by boxmailman
so, my assignment is due in 4 hours, but i can't solve this eqn

dy/dt = -y^4 + 2y^3 + 63y^2

my TA told me to isolate the equation for -y^2, and that's what i got:

dy/dt = -y^2(y^2 - 2y - 63)
= -y^2(y - 9)(y + 7)

i have no clue to solve it...
Separate the variables to get $\displaystyle -\int\frac{\,dy}{y^2(y-9)(y+7)}=\int\,dx$

Apply the method of partial fractions to integrate the LHS of the equation.

Can you take it from here?

3. thnx a lot, that was really helpful!!!