I am taking an Engineering Math class. When it comes of differential equations with y2 included in t

or5a2dosz80z

or5a2dosz80z

Answered question

2022-06-02

I am taking an Engineering Math class. When it comes of differential equations with y2 included in the question I am lost on the procedure used to solve it. Bernoulli method does work because its not in form required and homogeneous equations doesn't work because of different degrees.
These are a few that had me stumped (Solving any one will be appreciated.)
1. y = ( y 2 + 9 ) / ( x y + 3 y )
2. y ln ( x ) y = ( y 2 + 36 ) / x
3. y = ( x 2 y 4 x 2 ) / y 3
Thanks!

Answer & Explanation

Baron Haynes

Baron Haynes

Beginner2022-06-03Added 2 answers

For number one, here's a basic concept to help you get started:
y = y 2 + 9 x y + 3 y
y = y 2 + 9 y ( x + 3 )
NOTE THE SEPARATION
y y 2 + 9 d y d x = y 2 + 9 y ( x + 3 ) y y 2 + 9
y y 2 + 9 d y = 1 x + 3 d x
ln | y 2 + 9 | 2 = ln | x + 3 | + C
ln | y 2 + 9 | = 2 ln | x + 3 | + C
y 2 + 9 = C ( x + 3 ) 2
Can you use this technique to solve the other problems?
Imani Bentley

Imani Bentley

Beginner2022-06-04Added 2 answers

Start with the first one. Multiply across to get ( x y + 3 y ) y = y 2 + 9. Now notice that the lhs has a factor y and that y y is what you get if you differentiate y 2 . What does that suggest?
Now look at the second one. Again we have a y y . What happens if we try the same trick again?

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