1.21 problem 21

Internal problem ID [5734]

Book: Ordinary differential equations and calculus of variations. Makarets and Reshetnyak. Wold Scientific. Singapore. 1995
Section: Chapter 1. First order differential equations. Section 1.1 Separable equations problems. page 7
Problem number: 21.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [_separable]

\[ \boxed {y^{\prime }-{\mathrm e}^{x -y}=0} \]

Solution by Maple

Time used: 0.0 (sec). Leaf size: 9

dsolve(diff(y(x),x)=exp(x-y(x)),y(x), singsol=all)
 

\[ y \left (x \right ) = \ln \left ({\mathrm e}^{x}+c_{1} \right ) \]

Solution by Mathematica

Time used: 0.743 (sec). Leaf size: 12

DSolve[y'[x]==Exp[x-y[x]],y[x],x,IncludeSingularSolutions -> True]
 

\[ y(x)\to \log \left (e^x+c_1\right ) \]