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Question

Question: Solution of (xy<sup>4</sup> + y) dx – xdy = 0 is...

Solution of (xy4 + y) dx – xdy = 0 is

A

x44+(xy)3=c\frac{x^{4}}{4} + \left( \frac{x}{y} \right)^{3} = c

B

x44+13(xy)2=c\frac{x^{4}}{4} + \frac{1}{3}\left( \frac{x}{y} \right)^{2} = c

C

x44+3(xy)2=c\frac{x^{4}}{4} + 3\left( \frac{x}{y} \right)^{2} = c

D

None of these

Answer

x44+(xy)3=c\frac{x^{4}}{4} + \left( \frac{x}{y} \right)^{3} = c

Explanation

Solution

Rearrange the diff. equation xdx + ydxxdyy4\frac{ydx - xdy}{y^{4}} = 0

x3dx+ x2y2ydxxdyy2\frac{x^{2}}{y^{2}} \cdot \frac{ydx - xdy}{y^{2}} = 0

x3dx+ ddx\frac{d}{dx} (xy)\left( \frac{x}{y} \right) = 0

integratings x44+13(xy)3\frac{x^{4}}{4} + \frac{1}{3}\left( \frac{x}{y} \right)^{3} + c