6.20 problem 20

Internal problem ID [1049]

Book: Elementary differential equations with boundary value problems. William F. Trench. Brooks/Cole 2001
Section: Chapter 2, First order equations. Exact equations. Section 2.5 Page 79
Problem number: 20.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [_separable]

Solve \begin {gather*} \boxed {\left (y^{3}-1\right ) {\mathrm e}^{x}+3 y^{2} \left ({\mathrm e}^{x}+1\right ) y^{\prime }=0} \end {gather*} With initial conditions \begin {align*} [y \relax (0) = 0] \end {align*}

Solution by Maple

Time used: 0.154 (sec). Leaf size: 91

dsolve([((y(x)^3-1)*exp(x))+(3*y(x)^2*(exp(x)+1))*diff(y(x),x)=0,y(0) = 0],y(x), singsol=all)
 

\begin{align*} y \relax (x ) = \frac {\left (\left ({\mathrm e}^{x}-1\right ) \left (1+{\mathrm e}^{x}\right )^{2}\right )^{\frac {1}{3}}}{1+{\mathrm e}^{x}} \\ y \relax (x ) = \frac {\left (i \sqrt {3}-1\right ) \left (\left ({\mathrm e}^{x}-1\right ) \left (1+{\mathrm e}^{x}\right )^{2}\right )^{\frac {1}{3}}}{2+2 \,{\mathrm e}^{x}} \\ y \relax (x ) = -\frac {\left (1+i \sqrt {3}\right ) \left (\left ({\mathrm e}^{x}-1\right ) \left (1+{\mathrm e}^{x}\right )^{2}\right )^{\frac {1}{3}}}{2+2 \,{\mathrm e}^{x}} \\ \end{align*}

Solution by Mathematica

Time used: 0.527 (sec). Leaf size: 73

DSolve[{((y[x]^3-1)*Exp[x])+(3*y[x]^2*(Exp[x]+1))*y'[x]==0,y[0]==0},y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to \sqrt [3]{\tanh \left (\frac {x}{2}\right )} \\ y(x)\to -\frac {1}{2} i \left (\sqrt {3}-i\right ) \sqrt [3]{\tanh \left (\frac {x}{2}\right )} \\ y(x)\to \frac {1}{2} i \left (\sqrt {3}+i\right ) \sqrt [3]{\tanh \left (\frac {x}{2}\right )} \\ \end{align*}