2.8 problem 8

Internal problem ID [486]

Book: Elementary differential equations and boundary value problems, 10th ed., Boyce and DiPrima
Section: Section 2.2. Page 48
Problem number: 8.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [_separable]

Solve \begin {gather*} \boxed {y^{\prime }-\frac {x^{2}}{1+y^{2}}=0} \end {gather*}

Solution by Maple

Time used: 0.002 (sec). Leaf size: 353

dsolve(diff(y(x),x) = x^2/(1+y(x)^2),y(x), singsol=all)
 

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

Solution by Mathematica

Time used: 2.108 (sec). Leaf size: 234

DSolve[y'[x]== x^2/(1+y[x]^2),y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to \frac {-2+\sqrt [3]{2} \left (x^3+\sqrt {4+\left (x^3+3 c_1\right ){}^2}+3 c_1\right ){}^{2/3}}{2^{2/3} \sqrt [3]{x^3+\sqrt {4+\left (x^3+3 c_1\right ){}^2}+3 c_1}} \\ y(x)\to \frac {2 \sqrt [3]{-2}+(-2)^{2/3} \left (x^3+\sqrt {4+\left (x^3+3 c_1\right ){}^2}+3 c_1\right ){}^{2/3}}{2 \sqrt [3]{x^3+\sqrt {4+\left (x^3+3 c_1\right ){}^2}+3 c_1}} \\ y(x)\to \frac {\text {Root}\left [\text {$\#$1}^3+2\&,2\right ]}{\sqrt [3]{x^3+\sqrt {4+\left (x^3+3 c_1\right ){}^2}+3 c_1}}-\sqrt [3]{-\frac {1}{2}} \sqrt [3]{x^3+\sqrt {4+\left (x^3+3 c_1\right ){}^2}+3 c_1} \\ \end{align*}