# HW help

1. Feb 14, 2008

### gonzalo12345

HW help!!!

1. The problem statement, all variables and given/known data

consider the differential equation dy/dx = (y-1)^2 cos(Πx)

a.There is a horizontal line with y =c that satisfies this equation. Find the value of c
b. Find the particular solution y =f(x) tot the differential equation with the initial condition f(1) = 0

2. Relevant equations

n/a

3. The attempt at a solution

I tried to do the problem, but I cant separate the y variables from the x, help!

2. Feb 14, 2008

### PingPong

(a) What happens when you plug y=c to the differential equation? You should get just an equation depending on c (and x, but if you restrict x, you can divide it out).
(b) Try multiplying each side by dx/(y-1)^2 and integrating directly. Then, you can either use your initial conditions as your integration limits or plug them in to find your integration constant.

3. Feb 14, 2008

### gonzalo12345

I got it, I got c=1 thanks

4. Feb 15, 2008

### HallsofIvy

Staff Emeritus
While it is, in fact, almost trivial to separate x and y ((y-1)2 and cos($\pi$), in effect, are separated- they are multiplied), you don't have to find the general solution to answer (b)!

5. Feb 16, 2008

### kaisxuans

i dont know much but i do know that u need to get your basics right. come see the lastest post in my blog. the web link may be of help

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