5.7 problem 7

Internal problem ID [85]

Book: Differential equations and linear algebra, 3rd ed., Edwards and Penney
Section: Section 1.6, Substitution methods and exact equations. Page 74
Problem number: 7.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [[_homogeneous, class A], _rational, _Bernoulli]

Solve \begin {gather*} \boxed {x y^{2} y^{\prime }-x^{3}-y^{3}=0} \end {gather*}

Solution by Maple

Time used: 0.0 (sec). Leaf size: 74

dsolve(x*y(x)^2*diff(y(x),x) = x^3+y(x)^3,y(x), singsol=all)
 

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

Solution by Mathematica

Time used: 0.175 (sec). Leaf size: 63

DSolve[x*y[x]^2*y'[x] == x^3+y[x]^3,y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to x \sqrt [3]{3 \log (x)+c_1} \\ y(x)\to -\sqrt [3]{-1} x \sqrt [3]{3 \log (x)+c_1} \\ y(x)\to (-1)^{2/3} x \sqrt [3]{3 \log (x)+c_1} \\ \end{align*}