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I'm brand new to Mathematica. I am trying to solve a heat equation problem, but I keep getting back the input on the output line.

The problem:

enter image description here

In:

heatequation = D[u[x, t], t] == 5*D[u[x, t], {x, 2}] + D[u[x, t], x] - u[x, t];
boundarycondition = {Derivative[1, 0][u][0, t] == 0, u[1, t] == 0};
initialcondition = u[x, 0] == 3;
sol = DSolve[{heatequation, initialcondition, boundarycondition}, u [x, t], {x, t}]

Out:

DSolve[{(u^(0,1))[x,t]==-u[x,t]+(u^(1,0))[x,t]+5 (u^(2,0))[x,t],u[x,0]==3,{(u^(1,0))[0,t]==0,u[1,t]==0}},u[x,t],{x,t}]

Example: https://blog.wolfram.com/2016/01/07/new-in-the-wolfram-language-symbolic-pdes/

user21
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rededx
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  • DSolve[]'s support for PDE equations is still somewhat limited, so don't be surprised if some things don't work yet.See: Results on web page: https://www.12000.org/my_notes/pde_in_CAS/maple_2019_and_mma_12/index.htm – Mariusz Iwaniuk Dec 02 '19 at 15:57
  • And this problem probably doesn't have a simple symbolic solution. (Somewhat related: https://mathematica.stackexchange.com/q/155817/1871) Is it necessary for you to obtain a symbolic solution? If not, try NDSolve instead. – xzczd Dec 04 '19 at 06:48
  • Also, the problem can be solved with Laplace transform symbolically. We already have a number of related posts, you can have a look: https://mathematica.stackexchange.com/search?tab=votes&q=%5bdifferential-equations%5d%20LaplaceTransform – xzczd Dec 04 '19 at 07:19

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