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The curve amongst the family of curves responded by the differential equation, (x^2 - y^2)dx +2xy\: \: \: dy = 0 which passes through (1,1), is:

  • Option 1)

    A hyperbola with the transverse axis along the x-axis

  • Option 2)

    A circle with centre on the x-axis

  • Option 3)

    an ellipse with the major axis along the y-axis.

  • Option 4)

    A circle with centre on the y-axis

Answers (1)

best_answer

 

Homogeneous Differential Equation -

A function

f\left ( x,y \right ) 

is called homogeneous function of  degree n, if

f\left (dx,dy \right )=d^{n}\left ( x,y \right )

- wherein

eg:

f\left ( x,y \right )=x^{2}y^{2}-xy^{3}

 

 

Homogeneous Differential Equation -

Put

\frac{y}{x}=v

\frac{dy}{dx}=v+\frac{xdv}{dx}

-

(x^{2}-y^{2})dx+2xy\: dy=0

The D.E. can be written as 

\frac{dy}{dx}=\frac{y^{2}-x^{2}}{2xy}

from the concept 

put \frac{y}{x}=v

=>\frac{dy}{dx}=v+x\frac{dv}{dx}

=>\int \frac{2v}{v^{2}+1}dv=\int \frac{-dx}{x}

On Integrating

\ln (v^{2}+1)=-\ln (x)+C

(y^{2}+x^{2})=Cx

Passes through (1,1)

=>C=2

y^{2}+x^{2}=2x

 

 

 

 


Option 1)

A hyperbola with the transverse axis along the x-axis

Option 2)

A circle with centre on the x-axis

Option 3)

an ellipse with the major axis along the y-axis.

Option 4)

A circle with centre on the y-axis

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