symbolic constants in CAS

[jgreenb2]

I'm a self-confessed CAS newbie -- I never used it on my 48 or 50. But now I want to explore it a bit and I'm confused.

If I want to find the Laplace transform of exp(x) I execute:

laplace(exp(x),x,t) and correctly get 1/(t-1) as a result.

Now if I want to symbolically evaluate exp(a*x) for an undetermined constant 'a' I should get 1/(t-a) as the answer. But if I use 'A' as the constant, it's evaluated and I get 1/(t-3) as the answer (assuming 3 is stored in A).

If I try using 'a' as the constant:

laplace(exp(a*x),x,t) I get an error because 'a' is undefined.

How do I enter laplace(exp(a*x),x,t) and get back 1/(t-a) ???