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dy-dx-y-2-x-2-y-x-




Question Number 96217 by john santu last updated on 30/May/20
(dy/dx) = (((y^2 −x^2 +y)/x))
$$\frac{\mathrm{dy}}{\mathrm{dx}}\:=\:\left(\frac{\mathrm{y}^{\mathrm{2}} −\mathrm{x}^{\mathrm{2}} +\mathrm{y}}{\mathrm{x}}\right)\: \\ $$
Answered by bobhans last updated on 30/May/20
set y = xz ⇒ (dy/dx) = z + x (dz/dx)  z + x (dz/dx) = ((x^2 z^2 −x^2 + xz)/x)  z + x (dz/dx) = xz^2 −x+ z ⇒ x (dz/dx) = x(z^2 −1)  (dz/(z^2 −1)) = dx ⇒ ∫ (1/(z+1))−(1/(z−1)) dz = −2 dx  ln ∣((z+1)/(z−1))∣ = −2x + c ⇒ ((z+1)/(z−1)) = Ce^(−2x)   ((y+x)/(y−x)) = Ce^(−2x)
$$\mathrm{set}\:\mathrm{y}\:=\:{xz}\:\Rightarrow\:\frac{{dy}}{{dx}}\:=\:{z}\:+\:{x}\:\frac{{dz}}{{dx}} \\ $$$${z}\:+\:{x}\:\frac{{dz}}{{dx}}\:=\:\frac{{x}^{\mathrm{2}} {z}^{\mathrm{2}} −{x}^{\mathrm{2}} +\:{xz}}{{x}} \\ $$$${z}\:+\:{x}\:\frac{{dz}}{{dx}}\:=\:{xz}^{\mathrm{2}} −{x}+\:{z}\:\Rightarrow\:{x}\:\frac{{dz}}{{dx}}\:=\:{x}\left({z}^{\mathrm{2}} −\mathrm{1}\right) \\ $$$$\frac{{dz}}{{z}^{\mathrm{2}} −\mathrm{1}}\:=\:{dx}\:\Rightarrow\:\int\:\frac{\mathrm{1}}{{z}+\mathrm{1}}−\frac{\mathrm{1}}{{z}−\mathrm{1}}\:{dz}\:=\:−\mathrm{2}\:{dx} \\ $$$$\mathrm{ln}\:\mid\frac{{z}+\mathrm{1}}{{z}−\mathrm{1}}\mid\:=\:−\mathrm{2}{x}\:+\:{c}\:\Rightarrow\:\frac{{z}+\mathrm{1}}{{z}−\mathrm{1}}\:=\:{Ce}^{−\mathrm{2}{x}} \\ $$$$\frac{{y}+{x}}{{y}−{x}}\:=\:{Ce}^{−\mathrm{2}{x}} \: \\ $$$$ \\ $$

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