#### 6.4.18 6.4

6.4.18.1 [1130] Problem 1
6.4.18.2 [1131] Problem 2
6.4.18.3 [1132] Problem 3
6.4.18.4 [1133] Problem 4
6.4.18.5 [1134] Problem 5

##### 6.4.18.1 [1130] Problem 1

problem number 1130

Added March 9, 2019.

Problem Chapter 4.6.4.1, from Handbook of ﬁrst order partial diﬀerential equations by Polyanin, Zaitsev, Moussiaux.

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

$a w_x + b w_y = c \cot (\lambda x+\mu y) w$

Mathematica

$\left \{\left \{w(x,y)\to c_1\left (y-\frac{b x}{a}\right ) \exp \left (\frac{c (\log (\tan (\lambda x+\mu y))+\log (\cos (\lambda x+\mu y)))}{a \lambda +b \mu }\right )\right \}\right \}$

Maple

$w \left ( x,y \right ) ={\it \_F1} \left ({\frac{ya-bx}{a}} \right ) \left ( \left ( \cot \left ( \lambda \,x+\mu \,y \right ) \right ) ^{2}+1 \right ) ^{-{\frac{c}{2\,a\lambda +2\,b\mu }}}$

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##### 6.4.18.2 [1131] Problem 2

problem number 1131

Added March 9, 2019.

Problem Chapter 4.6.4.2, from Handbook of ﬁrst order partial diﬀerential equations by Polyanin, Zaitsev, Moussiaux.

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

$a w_x + b w_y = (c \cot (\lambda x)+ k \cot (\mu y) ) w$

Mathematica

$\left \{\left \{w(x,y)\to \sin ^{\frac{c}{a \lambda }}(\lambda x) c_1\left (y-\frac{b x}{a}\right ) e^{\frac{k (\log (\tan (\mu y))+\log (\cos (\mu y)))}{b \mu }}\right \}\right \}$

Maple

$w \left ( x,y \right ) ={\it \_F1} \left ({\frac{ya-bx}{a}} \right ) \left ( \left ( \cot \left ( \lambda \,x \right ) \right ) ^{2}+1 \right ) ^{-1/2\,{\frac{c}{a\lambda }}} \left ( \left ( \cot \left ( \mu \,y \right ) \right ) ^{2}+1 \right ) ^{-1/2\,{\frac{k}{b\mu }}}$

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##### 6.4.18.3 [1132] Problem 3

problem number 1132

Added March 9, 2019.

Problem Chapter 4.6.4.3, from Handbook of ﬁrst order partial diﬀerential equations by Polyanin, Zaitsev, Moussiaux.

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

$x w_x + y w_y = a x \cot (\lambda x+ \mu y) w$

Mathematica

$\left \{\left \{w(x,y)\to c_1\left (\frac{y}{x}\right ) \exp \left (\frac{a x (\log (\tan (\lambda x+\mu y))+\log (\cos (\lambda x+\mu y)))}{\lambda x+\mu y}\right )\right \}\right \}$

Maple

$w \left ( x,y \right ) ={\it \_F1} \left ({\frac{y}{x}} \right ) \left ( \left ( \cot \left ( \lambda \,x+\mu \,y \right ) \right ) ^{2}+1 \right ) ^{-1/2\,{a \left ({\frac{\mu \,y}{x}}+\lambda \right ) ^{-1}}}$

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##### 6.4.18.4 [1133] Problem 4

problem number 1133

Added March 9, 2019.

Problem Chapter 4.6.4.4, from Handbook of ﬁrst order partial diﬀerential equations by Polyanin, Zaitsev, Moussiaux.

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

$a w_x + b \cot ^n(\lambda x) w_y = (c \cot ^m(\mu x)+s \cot ^k(\beta y)) w$

Mathematica

$\left \{\left \{w(x,y)\to c_1\left (\frac{b \cot ^{n+1}(\lambda x) \, _2F_1\left (1,\frac{n+1}{2};\frac{n+3}{2};-\cot ^2(\lambda x)\right )}{a \lambda n+a \lambda }+y\right ) \exp \left (\int _1^x\frac{s \cot ^k\left (\frac{\beta \left (b \, _2F_1\left (1,\frac{n+1}{2};\frac{n+3}{2};-\cot ^2(\lambda x)\right ) \cot ^{n+1}(\lambda x)+a \lambda (n+1) y-b \cot ^{n+1}(\lambda K[1]) \, _2F_1\left (1,\frac{n+1}{2};\frac{n+3}{2};-\cot ^2(\lambda K[1])\right )\right )}{a \lambda (n+1)}\right )+c \cot ^m(\mu K[1])}{a}dK[1]\right )\right \}\right \}$

Maple

$w \left ( x,y \right ) ={\it \_F1} \left ( -\int \!{\frac{b \left ( \cot \left ( \lambda \,x \right ) \right ) ^{n}}{a}}\,{\rm d}x+y \right ){{\rm e}^{\int ^{x}\!{\frac{1}{a} \left ( c \left ( \cot \left ( \mu \,{\it \_b} \right ) \right ) ^{m}+s \left ( -\cot \left ( \beta \, \left ( -\int \!{\frac{b \left ( \cot \left ({\it \_b}\,\lambda \right ) \right ) ^{n}}{a}}\,{\rm d}{\it \_b}+\int \!{\frac{b \left ( \cot \left ( \lambda \,x \right ) \right ) ^{n}}{a}}\,{\rm d}x-y \right ) \right ) \right ) ^{k} \right ) }{d{\it \_b}}}}$

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##### 6.4.18.5 [1134] Problem 5

problem number 1134

Added March 9, 2019.

Problem Chapter 4.6.4.5, from Handbook of ﬁrst order partial diﬀerential equations by Polyanin, Zaitsev, Moussiaux.

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

$a w_x + b \cot ^n(\lambda y) w_y = (c \cot ^m(\mu x)+s \cot ^k(\beta y)) w$

Mathematica

$\left \{\left \{w(x,y)\to c_1\left (\frac{\cot ^{1-n}(\lambda y) \, _2F_1\left (1,\frac{1}{2}-\frac{n}{2};\frac{3}{2}-\frac{n}{2};-\cot ^2(\lambda y)\right )}{\lambda (n-1)}-\frac{b x}{a}\right ) \exp \left (\int _1^y\frac{\left (s \cot ^k(\beta K[1])+c \cot ^m\left (\frac{a \mu \, _2F_1\left (1,\frac{1}{2}-\frac{n}{2};\frac{3}{2}-\frac{n}{2};-\cot ^2(\lambda y)\right ) \cot ^{1-n}(\lambda y)+b \lambda \mu x-b \lambda \mu n x-a \mu \cot ^{1-n}(\lambda K[1]) \, _2F_1\left (1,\frac{1}{2}-\frac{n}{2};\frac{3}{2}-\frac{n}{2};-\cot ^2(\lambda K[1])\right )}{b \lambda -b \lambda n}\right )\right ) \cot ^{-n}(\lambda K[1])}{b}dK[1]\right )\right \}\right \}$

Maple

$w \left ( x,y \right ) ={\it \_F1} \left ( -{\frac{a\int \! \left ( \cot \left ( y\lambda \right ) \right ) ^{-n}\,{\rm d}y}{b}}+x \right ){{\rm e}^{\int ^{y}\!{\frac{ \left ( \cot \left ({\it \_b}\,\lambda \right ) \right ) ^{-n}}{b} \left ( c \left ( -\cot \left ( -\mu \,\int \!{\frac{ \left ( \cot \left ({\it \_b}\,\lambda \right ) \right ) ^{-n}a}{b}}\,{\rm d}{\it \_b}-\mu \, \left ( -{\frac{a\int \! \left ( \cot \left ( y\lambda \right ) \right ) ^{-n}\,{\rm d}y}{b}}+x \right ) \right ) \right ) ^{m}+s \left ( \cot \left ( \beta \,{\it \_b} \right ) \right ) ^{k} \right ) }{d{\it \_b}}}}$

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