
Quincy L. answered 05/05/20
Former high school teacher and long-time math tutor
I'll assume you are talking about horizontal asymptotes. Any exponential function of the form f(x) = a·bx + c (where b ≠ 1) has a horizontal asymptote of y = c. If you don't see a "c" being added or subtracted, the asymptote is y = 0.
Examples:
f(x) = 7·2x + 4 has an asymptote of y = 4
g(x) = 0.6·10x - 15 has an asymptote of y = -15
h(x) = 3·(-0.2)x has an asymptote of y = 0 since there is nothing being added or subtracted from the function.
I hope that helps out.