1. EXAMPLE 1
Write a function rule
Tell whether the table represents an exponential function. If so, write a rule for the function. x y –1 1 2 3 9 +1 a.

2. EXAMPLE 1
Write a function rule
The y-values are multiplied by 3 for each increase of 1 in x, so the table represents an exponential function of the form y = abx with b = 3.
The value of y when x = 0 is , so a = . 1 3
The table represents the exponential function y = x. 1 3

3. EXAMPLE 1
Write a function rule x y –1 2 1 +1 4 16 b. 1 4
The y-values are multiplied by for each increase of 1 in x, so the table represents an exponential function of the form y = abx with b = .

4. EXAMPLE 1
Write a function rule
The value of y when x = 0 is 1, so a = 1. 1 4
The table represents the exponential function y = x

5. 5 1 GUIDED PRACTICE for Example 1
Tell whether the table represents an exponential function. If so, write a rule for the function. 1 5 x y –1 2 25
ANSWER
yes; y = ( )x 1 5