Explanation
Let the arbitrary point be $$x,y.$$ Now the slope of the line joining the origin and the point is $$=\dfrac{y-0}{x-0}$$ $$=\dfrac{y}{x}$$. The equation of the curve $$y=f(x)$$. Now slope of the tangent $$=\dfrac{dy}{dx}$$ $$=\dfrac{y}{2x}$$ ... as per the given condition. Hence $$2\dfrac{dy}{y}=\dfrac{dx}{x}$$ Integrating both sides we get $$2\ln y=\ln x+\ln c$$ Now $$y_{x=1}=2$$ Hence $$2\ln (2)=\ln (1)+\ln (c)$$ Or $$c=2^{2}=4$$ Hence $$2\ln y=\ln x+\ln 4$$ Or $$\ln (y^{2})=\ln 4x$$ Or $$y^{2}=4x$$ is the required equation. This is an equation of parabola.
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