7.3.27 8.3

7.3.27.1 [1007] Problem 1

problem number 1007

Added Feb. 11, 2019.

Problem Chapter 3.8.3.1 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\) \[ a w_x + b w_y = f(\alpha x+\beta y) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = a*D[w[x, y], x] + b*D[w[x, y], y] == f[alpha*x + beta*y]; 
sol = AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\frac {f\left (\beta y+\alpha K[1]+\frac {b \beta (K[1]-x)}{a}\right )}{a}dK[1]+c_1\left (y-\frac {b x}{a}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*diff(w(x,y),x) +b*diff(w(x,y),y) =  f(alpha*x+beta*y); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {f \left (\frac {-\left (-\textit {\_a} +x \right ) b \beta +\left (\textit {\_a} \alpha +\beta y \right ) a}{a}\right )}{a}d \textit {\_a} +\textit {\_F1} \left (\frac {a y -b x}{a}\right )\]

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7.3.27.2 [1008] Problem 2

problem number 1008

Added Feb. 11, 2019.

Problem Chapter 3.8.3.2 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\) \[ x w_x + y w_y = x f(\frac {y}{x}) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = x*D[w[x, y], x] + y*D[w[x, y], y] == x*f[y/x]; 
sol = AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to x f\left (\frac {y}{x}\right )+c_1\left (\frac {y}{x}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  x*diff(w(x,y),x) +y*diff(w(x,y),y) =  x*f(y/x); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = x f \left (\frac {y}{x}\right )+\textit {\_F1} \left (\frac {y}{x}\right )\]

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7.3.27.3 [1009] Problem 3

problem number 1009

Added Feb. 11, 2019.

Problem Chapter 3.8.3.2 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\) \[ x w_x + y w_y = f(x^2+y^2) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = x*D[w[x, y], x] + y*D[w[x, y], y] == f[x^2 + y^2]; 
sol = AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\frac {f\left (\frac {\left (x^2+y^2\right ) K[1]^2}{x^2}\right )}{K[1]}dK[1]+c_1\left (\frac {y}{x}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  x*diff(w(x,y),x) +y*diff(w(x,y),y) =  f(x^2+y^2); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {f \left (\frac {\textit {\_a}^{2} y^{2}}{x^{2}}+\textit {\_a}^{2}\right )}{\textit {\_a}}d \textit {\_a} +\textit {\_F1} \left (\frac {y}{x}\right )\]

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7.3.27.4 [1010] Problem 4

problem number 1010

Added Feb. 11, 2019.

Problem Chapter 3.8.3.4 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\) \[ x w_x + y w_y = x f(\frac {y}{x})+ g(x^2+y^2) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = x*D[w[x, y], x] + y*D[w[x, y], y] == x*f[y/x] + g[x^2 + y^2]; 
sol = AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\left (f\left (\frac {y}{x}\right )+\frac {g\left (\frac {\left (x^2+y^2\right ) K[1]^2}{x^2}\right )}{K[1]}\right )dK[1]+c_1\left (\frac {y}{x}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  x*diff(w(x,y),x) +y*diff(w(x,y),y) =  x*f(y/x)+g(x^2+y^2); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {\textit {\_a} f \left (\frac {y}{x}\right )+g \left (\frac {\textit {\_a}^{2} y^{2}}{x^{2}}+\textit {\_a}^{2}\right )}{\textit {\_a}}d \textit {\_a} +\textit {\_F1} \left (\frac {y}{x}\right )\]

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7.3.27.5 [1011] Problem 5

problem number 1011

Added Feb. 11, 2019.

Problem Chapter 3.8.3.5 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\) \[ a x w_x + b y w_y = x^k f(x^n y^m) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = a*x*D[w[x, y], x] + b*y*D[w[x, y], y] == x^k*f[x^n*x^m]; 
sol = AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\frac {f\left (K[1]^{m+n}\right ) K[1]^{k-1}}{a}dK[1]+c_1\left (y x^{-\frac {b}{a}}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*x*diff(w(x,y),x) +b*y*diff(w(x,y),y) =  x^k*f(x^n*y^m); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {\textit {\_a}^{k -1} f \left (\textit {\_a}^{n} \left (y \,\textit {\_a}^{\frac {b}{a}} x^{-\frac {b}{a}}\right )^{m}\right )}{a}d \textit {\_a} +\textit {\_F1} \left (y \,x^{-\frac {b}{a}}\right )\]

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7.3.27.6 [1012] Problem 6

problem number 1012

Added Feb. 11, 2019.

Problem Chapter 3.8.3.6 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\) \[ m x w_x + n y w_y = f(a x^n + b y^m) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = m*x*D[w[x, y], x] + n*y*D[w[x, y], y] == f[a*x^n + b*x^m]; 
sol = AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\frac {f\left (b K[1]^m+a K[1]^n\right )}{m K[1]}dK[1]+c_1\left (y x^{-\frac {n}{m}}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  m*x*diff(w(x,y),x) +n*y*diff(w(x,y),y) =  f(a*x^n+b*y^m); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {f \left (a \,\textit {\_a}^{n}+b \left (y \,\textit {\_a}^{\frac {n}{m}} x^{-\frac {n}{m}}\right )^{m}\right )}{\textit {\_a} m}d \textit {\_a} +\textit {\_F1} \left (y \,x^{-\frac {n}{m}}\right )\]

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7.3.27.7 [1013] Problem 7

problem number 1013

Added Feb. 17, 2019.

Problem Chapter 3.8.3.7 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\)

\[ x^2 w_x + x y w_y = y^k f(\alpha x + \beta y) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde =  x^2*D[w[x, y], x] + x*y*D[w[x, y], y] == y^k*f[alpha*x + beta*y]; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\frac {f\left (\left (\alpha +\frac {\beta y}{x}\right ) K[1]\right ) \left (\frac {y K[1]}{x}\right )^k}{K[1]^2}dK[1]+c_1\left (\frac {y}{x}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  x^2*diff(w(x,y),x) +x*y*diff(w(x,y),y) =  y^k*f(alpha*x+beta*y); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {\left (\frac {\textit {\_a} y}{x}\right )^{k} f \left (\left (\alpha +\frac {\beta y}{x}\right ) \textit {\_a} \right )}{\textit {\_a}^{2}}d \textit {\_a} +\textit {\_F1} \left (\frac {y}{x}\right )\]

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7.3.27.8 [1014] Problem 8

problem number 1014

Added Feb. 17, 2019.

Problem Chapter 3.8.3.8 from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

Solve for \(w(x,y)\)

\[ \frac {f(x)}{f'(x)} w_x + \frac {g(y)}{g'(y)} w_y = h(f(x)+g(y)) \]

Mathematica ✓

ClearAll["Global`*"]; 
pde = (f[x]*D[w[x, y], x])/Derivative[1][f][x] + (g[y]*D[w[x, y], y])/Derivative[1][g][y] == h[f[x] + g[y]]; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y], {x, y}], 60*10]];
 

\[\left \{\left \{w(x,y)\to \int _1^x\frac {h\left (f(K[1])+g\left (\text {InverseFunction}\left [\text {InverseFunction}\left [g^{(-1)},1,1\right ],1,1\right ]\left [\frac {f(K[1]) \text {InverseFunction}\left [g^{(-1)},1,1\right ][y]}{f(x)}\right ]\right )\right ) f'(K[1])}{f(K[1])}dK[1]+c_1\left (\log \left (\frac {\text {InverseFunction}\left [g^{(-1)},1,1\right ][y]}{f(x)}\right )\right )\right \}\right \}\]

Maple ✓

restart; 
pde := f(x)/diff(f(x),x)*diff(w(x,y),x) +g(y)/diff(g(y),y)*diff(w(x,y),y) =  h(f(x)+g(y)); 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y)) ),output='realtime'));
 

\[w \left (x , y\right ) = \int _{}^{x}\frac {\left (\frac {d}{d \textit {\_a}}f \left (\textit {\_a} \right )\right ) h \left (\frac {\left (f \left (x \right )+g \left (y \right )\right ) f \left (\textit {\_a} \right )}{f \left (x \right )}\right )}{f \left (\textit {\_a} \right )}d \textit {\_a} +\textit {\_F1} \left (\ln \left (\frac {g \left (y \right )}{f \left (x \right )}\right )\right )\]

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