5.18 problem 134

5.18.1 Solving as quadrature ode
5.18.2 Maple step by step solution

Internal problem ID [3391]
Internal file name [OUTPUT/2884_Sunday_June_05_2022_08_45_10_AM_56072158/index.tex]

Book: Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section: Various 5
Problem number: 134.
ODE order: 1.
ODE degree: 1.

The type(s) of ODE detected by this program : "quadrature"

Maple gives the following as the ode type

[_quadrature]

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

5.18.1 Solving as quadrature ode

Integrating both sides gives \begin {align*} \int _{}^{y}\frac {1}{a f \left (\textit {\_a} \right )}d \textit {\_a} = x +c_{1} \end {align*}

Summary

The solution(s) found are the following \begin{align*} \tag{1} \int _{}^{y}\frac {1}{a f \left (\textit {\_a} \right )}d \textit {\_a} &= x +c_{1} \\ \end{align*}

Verification of solutions

\[ \int _{}^{y}\frac {1}{a f \left (\textit {\_a} \right )}d \textit {\_a} = x +c_{1} \] Verified OK.

5.18.2 Maple step by step solution

\[ \begin {array}{lll} & {} & \textrm {Let's solve}\hspace {3pt} \\ {} & {} & y^{\prime }-a f \left (y\right )=0 \\ \bullet & {} & \textrm {Highest derivative means the order of the ODE is}\hspace {3pt} 1 \\ {} & {} & y^{\prime } \\ \bullet & {} & \textrm {Solve for the highest derivative}\hspace {3pt} \\ {} & {} & y^{\prime }=a f \left (y\right ) \\ \bullet & {} & \textrm {Separate variables}\hspace {3pt} \\ {} & {} & \frac {y^{\prime }}{f \left (y\right )}=a \\ \bullet & {} & \textrm {Integrate both sides with respect to}\hspace {3pt} x \\ {} & {} & \int \frac {y^{\prime }}{f \left (y\right )}d x =\int a d x +c_{1} \\ \bullet & {} & \textrm {Cannot compute integral}\hspace {3pt} \\ {} & {} & \int \frac {y^{\prime }}{f \left (y\right )}d x =a x +c_{1} \end {array} \]

Maple trace

`Methods for first order ODEs: 
--- Trying classification methods --- 
trying a quadrature 
trying 1st order linear 
trying Bernoulli 
trying separable 
<- separable successful`
 

Solution by Maple

Time used: 0.0 (sec). Leaf size: 20

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

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

Solution by Mathematica

Time used: 0.295 (sec). Leaf size: 35

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

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