Solve the given differential equation by Separation of variables.

(1+x^4)dy + x(1+4y^2)dx = 0, y(1)=0

(3x^2 + 9xy + 5y^2)dx – (6x^2 +4xy)dy = 0, y(2) = -6

(3y^2-x^2 / y^5)dy/dx + x/2y^4 = 0, y(1) = 1

Dr/dQ + rsecQ = cosQ

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- Oct 15th 2009, 09:46 PMwyasserDifferential equations - seperation of variables
Solve the given differential equation by Separation of variables.

(1+x^4)dy + x(1+4y^2)dx = 0, y(1)=0

(3x^2 + 9xy + 5y^2)dx – (6x^2 +4xy)dy = 0, y(2) = -6

(3y^2-x^2 / y^5)dy/dx + x/2y^4 = 0, y(1) = 1

Dr/dQ + rsecQ = cosQ - Oct 16th 2009, 02:01 AMcraig
It will help people to answer your question if you write out your equations using LATEX.

For the first one:

Here divide both sides by , this will leave you with:

Hint, for the x variable consider using partial fractions to simplify the equation before you try and integrate.

The second one is a little harder.

For this one I would suggest using a substitution to simplify the equation a little before you attempt to separate the variables.

Let where , if we differentiate this equation with respect to we get

.

Substitute in these 2 values and see how you go.

When you've done these try and see what you can manage with the last two.

Hope this helps