Internal problem ID [4058]
Internal file name [OUTPUT/3551_Sunday_June_05_2022_09_37_50_AM_52256281/index.tex
]
Book: Ordinary differential equations and their solutions. By George Moseley Murphy.
1960
Section: Various 28
Problem number: 819.
ODE order: 1.
ODE degree: 2.
The type(s) of ODE detected by this program : "quadrature"
Maple gives the following as the ode type
[_quadrature]
\[ \boxed {{y^{\prime }}^{2}+\left (a x +b y\right ) y^{\prime }+a b x y=0} \] The ode \begin {align*} {y^{\prime }}^{2}+\left (a x +b y\right ) y^{\prime }+a b x y = 0 \end {align*}
is factored to \begin {align*} \left (a x +y^{\prime }\right ) \left (b y+y^{\prime }\right ) = 0 \end {align*}
Which gives the following equations \begin {align*} a x +y^{\prime } = 0\tag {1} \\ b y+y^{\prime } = 0\tag {2} \\ \end {align*}
Each of the above equations is now solved.
Solving ODE (1) Integrating both sides gives \begin {align*} y &= \int { -a x\,\mathop {\mathrm {d}x}}\\ &= -\frac {a \,x^{2}}{2}+c_{1} \end {align*}
Summary
The solution(s) found are the following \begin{align*} \tag{1} y &= -\frac {a \,x^{2}}{2}+c_{1} \\ \end{align*}
Verification of solutions
\[ y = -\frac {a \,x^{2}}{2}+c_{1} \] Verified OK.
Summary
The solution(s) found are the following \begin{align*} \tag{1} y &= -\frac {a \,x^{2}}{2}+c_{1} \\ \end{align*}
Verification of solutions
\[ y = -\frac {a \,x^{2}}{2}+c_{1} \] Verified OK.
Solving ODE (2) Integrating both sides gives \begin {align*} \int -\frac {1}{b y}d y &= x +c_{2}\\ -\frac {\ln \left (y \right )}{b}&=x +c_{2} \end {align*}
Solving for \(y\) gives these solutions \begin {align*} y_1&={\mathrm e}^{-b c_{2} -b x}\\ &=\frac {{\mathrm e}^{-b x}}{c_{2}} \end {align*}
Summary
The solution(s) found are the following \begin{align*} \tag{1} y &= \frac {{\mathrm e}^{-b x}}{c_{2}} \\ \end{align*}
Verification of solutions
\[ y = \frac {{\mathrm e}^{-b x}}{c_{2}} \] Verified OK.
Summary
The solution(s) found are the following \begin{align*} \tag{1} y &= \frac {{\mathrm e}^{-b x}}{c_{2}} \\ \end{align*}
Verification of solutions
\[ y = \frac {{\mathrm e}^{-b x}}{c_{2}} \] Verified OK.
\[ \begin {array}{lll} & {} & \textrm {Let's solve}\hspace {3pt} \\ {} & {} & {y^{\prime }}^{2}+\left (a x +b y\right ) y^{\prime }+a b x y=0 \\ \bullet & {} & \textrm {Highest derivative means the order of the ODE is}\hspace {3pt} 1 \\ {} & {} & y^{\prime } \\ \bullet & {} & \textrm {Solve for the highest derivative}\hspace {3pt} \\ {} & {} & \left [y^{\prime }=-a x , y^{\prime }=-b y\right ] \\ \square & {} & \textrm {Solve the equation}\hspace {3pt} y^{\prime }=-a x \\ {} & \circ & \textrm {Integrate both sides with respect to}\hspace {3pt} x \\ {} & {} & \int y^{\prime }d x =\int -a x d x +c_{1} \\ {} & \circ & \textrm {Evaluate integral}\hspace {3pt} \\ {} & {} & y=-\frac {a \,x^{2}}{2}+c_{1} \\ {} & \circ & \textrm {Solve for}\hspace {3pt} y \\ {} & {} & y=-\frac {a \,x^{2}}{2}+c_{1} \\ \square & {} & \textrm {Solve the equation}\hspace {3pt} y^{\prime }=-b y \\ {} & \circ & \textrm {Separate variables}\hspace {3pt} \\ {} & {} & \frac {y^{\prime }}{y}=-b \\ {} & \circ & \textrm {Integrate both sides with respect to}\hspace {3pt} x \\ {} & {} & \int \frac {y^{\prime }}{y}d x =\int -b d x +c_{1} \\ {} & \circ & \textrm {Evaluate integral}\hspace {3pt} \\ {} & {} & \ln \left (y\right )=-b x +c_{1} \\ {} & \circ & \textrm {Solve for}\hspace {3pt} y \\ {} & {} & y={\mathrm e}^{-b x +c_{1}} \\ \bullet & {} & \textrm {Set of solutions}\hspace {3pt} \\ {} & {} & \left \{y=-\frac {a \,x^{2}}{2}+c_{1} , y={\mathrm e}^{-b x +c_{1}}\right \} \end {array} \]
Maple trace
`Methods for first order ODEs: --- Trying classification methods --- trying a quadrature <- quadrature successful Methods for first order ODEs: --- Trying classification methods --- trying a quadrature trying 1st order linear <- 1st order linear successful`
✓ Solution by Maple
Time used: 0.0 (sec). Leaf size: 22
dsolve(diff(y(x),x)^2+(a*x+b*y(x))*diff(y(x),x)+a*b*x*y(x) = 0,y(x), singsol=all)
\begin{align*} y \left (x \right ) &= -\frac {a \,x^{2}}{2}+c_{1} \\ y \left (x \right ) &= c_{1} {\mathrm e}^{-b x} \\ \end{align*}
✓ Solution by Mathematica
Time used: 0.04 (sec). Leaf size: 34
DSolve[(y'[x])^2+(a x+b y[x])y'[x]+a b x y[x]==0,y[x],x,IncludeSingularSolutions -> True]
\begin{align*} y(x)\to c_1 e^{-b x} \\ y(x)\to -\frac {a x^2}{2}+c_1 \\ y(x)\to 0 \\ \end{align*}