5.20 problem 136

Internal problem ID [3393]

Book: Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section: Various 5
Problem number: 136.
ODE order: 1.
ODE degree: 1.

CAS Maple gives this as type [_separable]

\[ \boxed {y^{\prime }-f \left (x \right ) g \left (y\right )=0} \]

Solution by Maple

Time used: 0.016 (sec). Leaf size: 20

dsolve(diff(y(x),x) = f(x)*g(y(x)),y(x), singsol=all)
 

\[ \int f \left (x \right )d x -\left (\int _{}^{y \left (x \right )}\frac {1}{g \left (\textit {\_a} \right )}d \textit {\_a} \right )+c_{1} = 0 \]

Solution by Mathematica

Time used: 0.294 (sec). Leaf size: 42

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

\begin{align*} y(x)\to \text {InverseFunction}\left [\int _1^{\text {$\#$1}}\frac {1}{g(K[1])}dK[1]\&\right ]\left [\int _1^xf(K[2])dK[2]+c_1\right ] \\ y(x)\to g^{(-1)}(0) \\ \end{align*}