Chapter 4
Exponential and Logarithmic
Functions
4.1
The Exponetial Functions
Consider µ
1 + 1
¶
where is a positive integral. Then
lim →+∞ µ 1 + 1 ¶ = ≈ 27182818284
Theorem 50 If is any positive rational number, then
(1) lim →+∞ ³ 1 + ´ = ; (2) lim →+∞ ³ 1 + ´ =
Theorem 51 Let and be any numbers.
1. = +; 2. = −; 3. () = ; 4. 0 = 1; 5. −= 1 ; 6. If = then = 56
Exponetial Functions
Definition 22 An exponential function is a function that can be expressed
form
() =
where 0 and 6= 0
Properties 1. The domain of () =
is (−∞ ∞) and the range is
(0∞)
2. The function () = is continuous, increasing, and one-to-one on
R
3. The graph of () = is concave upward on its entire domain.
4. lim→−∞ = 0 and lim
→+∞ = +∞ 5 2.5 0 -2.5 -5 125 100 75 50 25 0 x y x y
5. lim→∞− = 0 and lim
→−∞− = +∞ 5 2.5 0 -2.5 -5 125 100 75 50 25 0 x y x y 57