1.33 problem Problem 47

Internal problem ID [12144]

Book: Differential equations and the calculus of variations by L. ElSGOLTS. MIR PUBLISHERS, MOSCOW, Third printing 1977.
Section: Chapter 1, First-Order Differential Equations. Problems page 88
Problem number: Problem 47.
ODE order: 1.
ODE degree: 2.

CAS Maple gives this as type [[_1st_order, _with_linear_symmetries], _Clairaut]

\[ \boxed {y-y^{\prime } x -{y^{\prime }}^{2}=0} \] With initial conditions \begin {align*} [y \left (2\right ) = -1] \end {align*}

Solution by Maple

Time used: 1.422 (sec). Leaf size: 17

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

\begin{align*} y \left (x \right ) &= 1-x \\ y \left (x \right ) &= -\frac {x^{2}}{4} \\ \end{align*}

Solution by Mathematica

Time used: 0.014 (sec). Leaf size: 21

DSolve[{y[x]==x*y'[x]+y'[x]^2,{y[2]==-1}},y[x],x,IncludeSingularSolutions -> True]
 

\begin{align*} y(x)\to 1-x \\ y(x)\to -\frac {x^2}{4} \\ \end{align*}