6.6.22 7.4

6.6.22.1 [1545] Problem 1

problem number 1545

Added May 31, 2019.

Problem Chapter 6.7.4.1, from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

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

\[ a w_x + b w_y + c \arccot ^n(\lambda x) \arccot ^k(\beta z) w_z = 0 \]

Mathematica ✓

ClearAll["Global`*"]; 
pde =  a*D[w[x, y,z], x] + b*D[w[x, y,z], y] +c*ArcCot[lambda*x]^n*ArcCot[beta*z]^k*D[w[x,y,z],z]==0; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y,z], {x, y,z}], 60*10]];
 

\[\left \{\left \{w(x,y,z)\to c_1\left (y-\frac {b x}{a},\int _1^z\cot ^{-1}(\beta K[1])^{-k}dK[1]-\int _1^x\frac {c \cot ^{-1}(\lambda K[2])^n}{a}dK[2]\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*diff(w(x,y,z),x)+ b*diff(w(x,y,z),y)+c*arccot(lambda*x)^n*arccot(beta*z)^k*diff(w(x,y,z),z)= 0; 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y,z))),output='realtime'));
 

\[w \left (x , y , z\right ) = f_{1} \left (\frac {a y -x b}{a}, -\int \operatorname {arccot}\left (\lambda x \right )^{n}d x +\frac {a \int \operatorname {arccot}\left (\beta z \right )^{-k}d z}{c}\right )\]

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6.6.22.2 [1546] Problem 2

problem number 1546

Added May 31, 2019.

Problem Chapter 6.7.4.2, from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

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

\[ a w_x + b w_y + c \arccot ^n(\lambda x) \arccot ^m(\beta y) \arccot ^k(\gamma z) w_z = 0 \]

Mathematica ✓

ClearAll["Global`*"]; 
pde =  a*D[w[x, y,z], x] + b*D[w[x, y,z], y] +c*ArcCot[lambda*x]^n*ArcCot[beta*y]^m*ArcCot[gamma*z]^k*D[w[x,y,z],z]==0; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y,z], {x, y,z}], 60*10]];
 

\[\left \{\left \{w(x,y,z)\to c_1\left (y-\frac {b x}{a},\int _1^z\cot ^{-1}(\gamma K[1])^{-k}dK[1]-\int _1^x\frac {c \cot ^{-1}(\lambda K[2])^n \left (\left (\frac {a \cot ^{-1}(\lambda K[2])^{-n} \text {InverseFunction}[\text {Inactive}[\text {Integrate}],1,2]\left [\int _1^x\frac {c \cot ^{-1}(\lambda K[2])^n \cot ^{-1}\left (\beta \left (y+\frac {b (K[2]-x)}{a}\right )\right )^m}{a}dK[2],\{K[2],1,x\}\right ]}{c}\right ){}^{\frac {1}{m}}\right ){}^m}{a}dK[2]\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*diff(w(x,y,z),x)+ b*diff(w(x,y,z),y)+c*arccot(lambda*x)^n*arccot(beta*y)^m*arccot(gamma1*z)^k*diff(w(x,y,z),z)= 0; 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y,z))),output='realtime'));
 

\[w \left (x , y , z\right ) = f_{1} \left (\frac {a y -b x}{a}, -\int _{}^{x}\operatorname {arccot}\left (\lambda \textit {\_a} \right )^{n} \operatorname {arccot}\left (\frac {\beta \left (a y -b \left (-\textit {\_a} +x \right )\right )}{a}\right )^{m}d \textit {\_a} +\frac {a \int \operatorname {arccot}\left (\gamma \operatorname {1} z \right )^{-k}d z}{c}\right )\]

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6.6.22.3 [1547] Problem 3

problem number 1547

Added May 31, 2019.

Problem Chapter 6.7.4.3, from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

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

\[ a w_x + b \arccot ^n(\lambda x) w_y + c \arccot ^k(\beta x) w_z = 0 \]

Mathematica ✓

ClearAll["Global`*"]; 
pde =  a*D[w[x, y,z], x] + b*ArcCot[lambda*x]^n*D[w[x, y,z], y] +c*ArcCot[beta*x]^k*D[w[x,y,z],z]==0; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y,z], {x, y,z}], 60*10]];
 

\[\left \{\left \{w(x,y,z)\to c_1\left (y-\int _1^x\frac {b \cot ^{-1}(\lambda K[1])^n}{a}dK[1],z-\int _1^x\frac {c \cot ^{-1}(\beta K[2])^k}{a}dK[2]\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*diff(w(x,y,z),x)+ b*arccot(lambda*x)^n*diff(w(x,y,z),y)+c*arccot(beta*x)^k*diff(w(x,y,z),z)= 0; 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y,z))),output='realtime'));
 

\[w \left (x , y , z\right ) = f_{1} \left (-\frac {b \int \operatorname {arccot}\left (\lambda x \right )^{n}d x}{a}+y , -\frac {c \int \operatorname {arccot}\left (\beta x \right )^{k}d x}{a}+z \right )\]

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6.6.22.4 [1548] Problem 4

problem number 1548

Added May 31, 2019.

Problem Chapter 6.7.4.4, from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

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

\[ a w_x + b \arccot ^n(\lambda x) w_y + c \arccot ^k(\beta z) w_z = 0 \]

Mathematica ✓

ClearAll["Global`*"]; 
pde =  a*D[w[x, y,z], x] + b*ArcCot[lambda*x]^n*D[w[x, y,z], y] +c*ArcCot[beta*z]^k*D[w[x,y,z],z]==0; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y,z], {x, y,z}], 60*10]];
 

\[\left \{\left \{w(x,y,z)\to c_1\left (y-\int _1^x\frac {b \cot ^{-1}(\lambda K[1])^n}{a}dK[1],\int _1^z\cot ^{-1}(\beta K[2])^{-k}dK[2]-\frac {c x}{a}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*diff(w(x,y,z),x)+ b*arccot(lambda*x)^n*diff(w(x,y,z),y)+c*arccot(beta*z)^k*diff(w(x,y,z),z)= 0; 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y,z))),output='realtime'));
 

\[w \left (x , y , z\right ) = f_{1} \left (-y +\frac {b \int \operatorname {arccot}\left (\lambda x \right )^{n}d x}{a}, -\int _{}^{y}{\operatorname {arccot}\left (\lambda \operatorname {RootOf}\left (b \int \operatorname {arccot}\left (\lambda x \right )^{n}d x -b \int _{}^{\textit {\_Z}}\operatorname {arccot}\left (\lambda \textit {\_b} \right )^{n}d \textit {\_b} +\textit {\_b} a -y a \right )\right )}^{-n}d \textit {\_b} +\frac {b \int \operatorname {arccot}\left (\beta z \right )^{-k}d z}{c}\right )\]

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6.6.22.5 [1549] Problem 5

problem number 1549

Added May 31, 2019.

Problem Chapter 6.7.4.5, from Handbook of first order partial differential equations by Polyanin, Zaitsev, Moussiaux.

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

\[ a w_x + b \arccot ^n(\lambda y) w_y + c \arccot ^k(\beta z) w_z = 0 \]

Mathematica ✓

ClearAll["Global`*"]; 
pde =  a*D[w[x, y,z], x] + b*ArcCot[lambda*y]^n*D[w[x, y,z], y] +c*ArcCot[beta*z]^k*D[w[x,y,z],z]==0; 
sol =  AbsoluteTiming[TimeConstrained[DSolve[pde, w[x, y,z], {x, y,z}], 60*10]];
 

\[\left \{\left \{w(x,y,z)\to c_1\left (\int _1^y\cot ^{-1}(\lambda K[1])^{-n}dK[1]-\frac {b x}{a},\int _1^z\cot ^{-1}(\beta K[2])^{-k}dK[2]-\frac {c x}{a}\right )\right \}\right \}\]

Maple ✓

restart; 
pde :=  a*diff(w(x,y,z),x)+ b*arccot(lambda*y)^n*diff(w(x,y,z),y)+c*arccot(beta*z)^k*diff(w(x,y,z),z)= 0; 
cpu_time := timelimit(60*10,CodeTools[Usage](assign('sol',pdsolve(pde,w(x,y,z))),output='realtime'));
 

\[w \left (x , y , z\right ) = f_{1} \left (-\frac {a \int \operatorname {arccot}\left (\lambda y \right )^{-n}d y}{b}+x , -\int \operatorname {arccot}\left (\lambda y \right )^{-n}d y +\frac {b \int \operatorname {arccot}\left (\beta z \right )^{-k}d z}{c}\right )\]

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