Differential Equations, implicit equation solving

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To find the differential equation for the implicit solution –4xy³ + 4xy³sin(x) = –1, the correct approach involves differentiating both sides with respect to x. The initial attempt yielded dy/dx = cos(x) - 4/(-3y³), which is incorrect. The discussion emphasizes that the goal is not to solve the equation but to express it in the form dy/dx = f(x, y). Proper differentiation of the implicit equation will lead to the required form, clarifying the relationship between x and y.
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Homework Statement


(b) Find the differential equation for which –4xy3 + 4xy3sin(x) = –1 is an implicit solution on the interval (0, pi/2). Write your answer in the form dy/dx = f (x,y) where f (x, y) depends on both x and y.



The Attempt at a Solution


I'm not too sure on how to go about solving for the differential equation after been given the implicit form. So farI got

dy/dx= cos(x)-4/(-3y3)
which I don't think is right, and


I'm not sure where to start?

(4xy3)(sin(x)-1)=-1

4y3=-1/[x(sin(x)-1]
and then do I take the derivative of this ^ to get my answer?
 
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But the question is not even asking you to solve the equation you get; you only need to get an equation whose implicit solution is the given function. If you differentiate both sides of the given equation with respect to x (as I assume you did), you should get the required answer.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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