Wolfram Cloud Document

If:

b[x,t]->

c

4

then:

(1,0)

b

[x,t]

=0 and

(0,1)

b

[x,t]

=0

In[]:=

-

2

′

h

[t]

2

c

+

2h[t]

(1,0)

b

[x,t]

2

c

0/.

(1,0)

b

[x,t]->0,

h[t]

4

-

b[x,t]h[t]

2

c

==0/.b[x,t]->

c

4

,

2Xi[2][t]

(0,1)

b

[x,t]

2

c

0/.

(0,1)

b

[x,t]->0

Out[]=

-

2

′

h

[t]

2

c

0,

h[t]

4

-

h[t]

4c

0,True

In[]:=

Solve

h[t]

4

-

h[t]

4c

0,h[t]

Out[]=

In[]:=

DSolve-

2

′

h

[t]

2

c

0,h[t],t

Out[]=

{{h[t]



1

}}

(*----------------------------------------------------------------------------------------------------------------------------*)

DSolve

2

′

Xi[2]

[t]

(1,0)

b

[x,t]

2

c

-

2

′′

Xi[2]

[t]

2

c

+2

(1,0)

f

[x,t]==0,-

2

′

h

[t]

2

c

+

2h[t]

(1,0)

b

[x,t]

2

c

0,

h[t]

4

-

b[x,t]h[t]

2

c

==0,{Xi[2][t],h[t],f[x,t],b[x,t]},{x,t}(*Syntaxiswrong!!Imeanthis:"{Xi[2][t],h[t],f[x,t],b[x,t]},{x,t}"*)(*Inthisexampleyouhave3equationsbut4unknowns?*)