# solving differential equations help

1. ## solving differential equations help

I need help in solving differential equations

Code:
```1- xy' - y = x^2

2- y' -y/x = x sinx

3- y' -3x^2 y = (4 x e ^(x^3))/sqrt(1+(x^2))

4- y'-y/x = x cos x```

•

2. ## Re: solving differential equations help

they are all first order linear ordinary differential equations
there are a variety of methods used, which may be found on the internet

you can check the answers with wolfram alpha:
go to the wolfram alpha website and type something like find y for xy' - y = x^2
enter and wait. it will give you the solution but won't tell you how to do it.

•

3. ## Re: solving differential equations help

Originally Posted by joniengr
I need help in solving differential equations

Code:
```1- xy' - y = x^2

2- y' -y/x = x sinx

3- y' -3x^2 y = (4 x e ^(x^3))/sqrt(1+(x^2))

4- y'-y/x = x cos x```

Hint:
Code:
`xy' - y = x^2 (y/x)'`
and
Code:
`y' -3x^2 y = (y e^(-x^3))' e^(x^3)`

Then
Code:
```1- x^2 (y/x)' = x^2  -----> solve  (y/x)' = 1

2- x (y/x)' = x sinx   -----> solve  (y/x)' = sinx

3- (y e^(-x^3))' e^(x^3) = (4 x e ^(x^3))/sqrt(1+(x^2)) -----> solve  (y e^(-x^3))' = (4 x)/sqrt(1+(x^2))

4- x (y/x)' = x cosx  -----> solve  (y/x)' = cosx```
All are easy to integrate.

--[[ ]]--