4.3 problem 3

Internal problem ID [4998]

Book: Fundamentals of Differential Equations. By Nagle, Saff and Snider. 9th edition. Boston. Pearson 2018.
Section: Chapter 2, First order differential equations. Review problems. page 79
Problem number: 3.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [_exact, _rational]

\[ \boxed {\left (x^{2}-\frac {2}{y^{3}}\right ) y^{\prime }+2 x y=3 x^{2}} \]

Solution by Maple

Time used: 0.016 (sec). Leaf size: 693

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

\begin{align*} y \left (x \right ) &= \frac {\frac {\left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {1}{3}}}{2}+\frac {2 \left (-x^{3}+c_{1} \right )^{2}}{\left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {1}{3}}}+x^{3}-c_{1}}{3 x^{2}} \\ y \left (x \right ) &= \frac {\frac {\left (-i \sqrt {3}-1\right ) \left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {2}{3}}}{4}+\left (\left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {1}{3}}+\left (i \sqrt {3}-1\right ) \left (x^{3}-c_{1} \right )\right ) \left (x^{3}-c_{1} \right )}{3 \left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {1}{3}} x^{2}} \\ y \left (x \right ) &= \frac {\frac {\left (i \sqrt {3}-1\right ) \left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {2}{3}}}{4}+\left (x^{3}-c_{1} \right ) \left (\left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {1}{3}}+\left (-i \sqrt {3}-1\right ) \left (x^{3}-c_{1} \right )\right )}{3 \left (8 x^{9}-24 c_{1} x^{6}+24 c_{1}^{2} x^{3}+12 \sqrt {3}\, \sqrt {-4 x^{9}+12 c_{1} x^{6}-12 c_{1}^{2} x^{3}+27 x^{4}+4 c_{1}^{3}}\, x^{2}-108 x^{4}-8 c_{1}^{3}\right )^{\frac {1}{3}} x^{2}} \\ \end{align*}

Solution by Mathematica

Time used: 13.843 (sec). Leaf size: 676

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

\begin{align*} y(x)\to \frac {2 \left (x^3+c_1\right )+\frac {2 \left (x^3+c_1\right ){}^2}{\sqrt [3]{x^9+3 c_1 x^6-\frac {27 x^4}{2}+3 c_1{}^2 x^3+\frac {3}{2} \sqrt {3} \sqrt {-x^4 \left (4 x^9+12 c_1 x^6-27 x^4+12 c_1{}^2 x^3+4 c_1{}^3\right )}+c_1{}^3}}+2^{2/3} \sqrt [3]{2 x^9+6 c_1 x^6-27 x^4+6 c_1{}^2 x^3+3 \sqrt {3} \sqrt {-x^4 \left (4 x^9+12 c_1 x^6-27 x^4+12 c_1{}^2 x^3+4 c_1{}^3\right )}+2 c_1{}^3}}{6 x^2} \\ y(x)\to \frac {4 \left (x^3+c_1\right )-\frac {2 i \left (\sqrt {3}-i\right ) \left (x^3+c_1\right ){}^2}{\sqrt [3]{x^9+3 c_1 x^6-\frac {27 x^4}{2}+3 c_1{}^2 x^3+\frac {3}{2} \sqrt {3} \sqrt {-x^4 \left (4 x^9+12 c_1 x^6-27 x^4+12 c_1{}^2 x^3+4 c_1{}^3\right )}+c_1{}^3}}+i 2^{2/3} \left (\sqrt {3}+i\right ) \sqrt [3]{2 x^9+6 c_1 x^6-27 x^4+6 c_1{}^2 x^3+3 \sqrt {3} \sqrt {-x^4 \left (4 x^9+12 c_1 x^6-27 x^4+12 c_1{}^2 x^3+4 c_1{}^3\right )}+2 c_1{}^3}}{12 x^2} \\ y(x)\to \frac {4 \left (x^3+c_1\right )+\frac {2 i \left (\sqrt {3}+i\right ) \left (x^3+c_1\right ){}^2}{\sqrt [3]{x^9+3 c_1 x^6-\frac {27 x^4}{2}+3 c_1{}^2 x^3+\frac {3}{2} \sqrt {3} \sqrt {-x^4 \left (4 x^9+12 c_1 x^6-27 x^4+12 c_1{}^2 x^3+4 c_1{}^3\right )}+c_1{}^3}}-2^{2/3} \left (1+i \sqrt {3}\right ) \sqrt [3]{2 x^9+6 c_1 x^6-27 x^4+6 c_1{}^2 x^3+3 \sqrt {3} \sqrt {-x^4 \left (4 x^9+12 c_1 x^6-27 x^4+12 c_1{}^2 x^3+4 c_1{}^3\right )}+2 c_1{}^3}}{12 x^2} \\ y(x)\to 0 \\ \end{align*}