8.23 problem 228

8.23.1 Solving as quadrature ode
8.23.2 Maple step by step solution

Internal problem ID [3484]
Internal file name [OUTPUT/2977_Sunday_June_05_2022_08_48_41_AM_61921181/index.tex]

Book: Ordinary differential equations and their solutions. By George Moseley Murphy. 1960
Section: Various 8
Problem number: 228.
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]

\[ \boxed {\left (a +x \right ) y^{\prime }=b x} \]

8.23.1 Solving as quadrature ode

Integrating both sides gives \begin {align*} y &= \int { \frac {b x}{a +x}\,\mathop {\mathrm {d}x}}\\ &= b \left (x -a \ln \left (a +x \right )\right )+c_{1} \end {align*}

Summary

The solution(s) found are the following \begin{align*} \tag{1} y &= b \left (x -a \ln \left (a +x \right )\right )+c_{1} \\ \end{align*}

Verification of solutions

\[ y = b \left (x -a \ln \left (a +x \right )\right )+c_{1} \] Verified OK.

8.23.2 Maple step by step solution

\[ \begin {array}{lll} & {} & \textrm {Let's solve}\hspace {3pt} \\ {} & {} & \left (a +x \right ) y^{\prime }=b x \\ \bullet & {} & \textrm {Highest derivative means the order of the ODE is}\hspace {3pt} 1 \\ {} & {} & y^{\prime } \\ \bullet & {} & \textrm {Solve for the highest derivative}\hspace {3pt} \\ {} & {} & y^{\prime }=\frac {b x}{a +x} \\ \bullet & {} & \textrm {Integrate both sides with respect to}\hspace {3pt} x \\ {} & {} & \int y^{\prime }d x =\int \frac {b x}{a +x}d x +c_{1} \\ \bullet & {} & \textrm {Evaluate integral}\hspace {3pt} \\ {} & {} & y=b \left (x -a \ln \left (a +x \right )\right )+c_{1} \\ \bullet & {} & \textrm {Solve for}\hspace {3pt} y \\ {} & {} & y=-a b \ln \left (a +x \right )+b x +c_{1} \end {array} \]

Maple trace

`Methods for first order ODEs: 
--- Trying classification methods --- 
trying a quadrature 
<- quadrature successful`
 

Solution by Maple

Time used: 0.016 (sec). Leaf size: 17

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

\[ y \left (x \right ) = -\ln \left (x +a \right ) a b +b x +c_{1} \]

Solution by Mathematica

Time used: 0.004 (sec). Leaf size: 19

DSolve[(a+x) y'[x]==b x,y[x],x,IncludeSingularSolutions -> True]
 

\[ y(x)\to -a b \log (a+x)+b x+c_1 \]