Differential Equations - Find equation of line

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Homework Help Overview

The problem involves finding the equation of a curve defined by a slope given in terms of x and y, specifically through the point (3, -2). The slope is expressed as (x^2 + y^2)/(y^3 - 2xy), and the context is within differential equations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to substitute the point (3, -2) into the slope equation and considers using the line equation to find the curve. They also explore transforming the slope equation into an exact equation and solving for it. Questions arise regarding the interpretation of the resulting equation and whether it represents the curve or the tangent line.

Discussion Status

Some participants provide feedback on the original poster's approach, suggesting that they are close to the solution but may have made an error in determining the constant. There is an ongoing exploration of the correct form of the equation and clarification of the relationship between the derived equation and the curve.

Contextual Notes

Participants note discrepancies in the value of the constant C and discuss the implications of this on the final equation of the curve. The conversation reflects uncertainty about the final form of the equation and its interpretation.

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Homework Statement



A curve passing through (3,-2) has a slope given by (x^2 + y^2)/(y^3 - 2xy). Find the equation of the curve.

Homework Equations





The Attempt at a Solution



My first thought was to plug in the points (3,-2) into the slope equation and plug them into the line equation (y - y1) = m(x - x1). Is that wrong? Seemed too easy for it to be a problem for differential equations..

So, I found that i could make the slope equation into an exact equation and solved for it.
I found that the answer i get is:
with c = -17
f(x,y) = x^3/3 + xy^2 - y^4/4 - 17
However that is not the equation of the curve. Is that the equation of the tangent line at (3,-2)?
I am stuck at this point, I am pretty sure I am done with 90% of the work, but I can't seem to figure out the equation of the curve from here on.
 
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Yes, you are pretty close, but you faltered a bit at the end.

The equation you were solving looked something like this:
Fx dx + Fy dy, where Fx = x2 + y2 and Fy = -y3 + 2xy

The solution to the equation above with the partials is F(x, y) = C, so you should have gotten (1/3)x3 - (1/4)y4 + xy2 = C.

Substitute y(3) = -2 into the equation above to find the constant C.
 
Yes I did that, realized that C = 17 (not negative). But I am still puzzled, what is the equation of the curve?
 
(1/3)x3 - (1/4)y4 + xy2 = 17.
 

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