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Student Support Forum > General > > "How to simplify with user defined identity"

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Please answer this:3+1 =



Original Message (ID '315973') By Bill Simpson:
Not a satisfying answer, but the best I can think of at the moment. "Solve" for Coth[a h] In[1]:= Map[a*#&,Map[1/#&,a Tanh[a h]==b Tanh[b h]]] Out[1]= Coth[a h] == a/b Coth[b h] Use that result as a replacement rule In[2]:= b Coth[a h]-a Coth[b h]/.Coth[a h]->a/b Coth[b h] Out[2]= 0 That is really no better than doing it manually. And it assumes, without checking, that a,b,h are nonzero.