1.7 problem 7

Internal problem ID [3152]

Book: Differential equations for engineers by Wei-Chau XIE, Cambridge Press 2010
Section: Chapter 2. First-Order and Simple Higher-Order Differential Equations. Page 78
Problem number: 7.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [_separable]

\[ \boxed {y^{3} x +\left (y+1\right ) {\mathrm e}^{-x} y^{\prime }=0} \]

Solution by Maple

Time used: 0.0 (sec). Leaf size: 71

dsolve(x*y(x)^3+(y(x)+1)*exp(-x)*diff(y(x),x)=0,y(x), singsol=all)
 

\begin{align*} y \left (x \right ) = -\frac {-1+\sqrt {2 \,{\mathrm e}^{x} x -2 \,{\mathrm e}^{x}+2 c_{1} +1}}{2 \left ({\mathrm e}^{x} x -{\mathrm e}^{x}+c_{1} \right )} y \left (x \right ) = \frac {1+\sqrt {2 \,{\mathrm e}^{x} x -2 \,{\mathrm e}^{x}+2 c_{1} +1}}{2 \,{\mathrm e}^{x} x +2 c_{1} -2 \,{\mathrm e}^{x}} \end{align*}

Solution by Mathematica

Time used: 9.963 (sec). Leaf size: 88

DSolve[x*y[x]^3+(y[x]+1)*Exp[-x]*y'[x]==0,y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to \frac {1-\sqrt {2 e^x (x-1)+1-2 c_1}}{2 e^x (x-1)-2 c_1} y(x)\to \frac {1+\sqrt {2 e^x (x-1)+1-2 c_1}}{2 e^x (x-1)-2 c_1} y(x)\to 0 \end{align*}