Use the definitions of the hyperbolic functions to find each of the following limits. (If the limit is infinite, enter '∞' or '-∞', as appropriate. If the limit does not otherwise exist, enter DNE.)
(a) lim x → ∞ tanh(x)
(b) lim x → -∞ tanh(x)
(c) lim x → ∞ sinh(x)
(d) lim x → -∞ sinh(x)
(e) lim x → ∞ sech(x)
(f) lim x → ∞ coth(x)
(g) lim x → 0+ coth(x)
(h) lim x → 0- coth(x)
(i) lim x → -∞ csch(x)
(j) lim x → ∞ sinh(x) ex