/ -b*x\ acos\E /
acos(E^(-b*x))
-b*x b*e ---------------- _____________ / -2*b*x \/ 1 - e
/ -2*b*x \ 2 | e | -b*x -b *|1 + -----------|*e | -2*b*x| \ 1 - e / ---------------------------- _____________ / -2*b*x \/ 1 - e
/ -4*b*x -2*b*x \ 3 | 3*e 4*e | -b*x b *|1 + -------------- + -----------|*e | 2 -2*b*x| | / -2*b*x\ 1 - e | \ \1 - e / / ------------------------------------------- _____________ / -2*b*x \/ 1 - e