Graphing Exponential Functions

Question

y=2^x-4

 

 

y=2^x+4

 

I'm confused by one being exponents but one isn't. How do I graph these? I try different x values like -1 and -2 but they don't appear similar to the answer in the book.

 

 

Answer 1

First, sketch the graph of y = 2^x.  Some points on the graph are (0,1), (1, 2), (2, 4), (3, 8), (-1, 0.5), (-2, 0.25).  

 

To obtain the graph of y = 2^x + 4, translate the graph of y = 2^x four units upward. So, (0, 1) moves to (0, 5), (1, 2) moves to (1, 6), etc.  

 

To obtain the graph of y = 2^x-4, translate the graph of y = 2^x four units to the right. So, (0, 1) moves to (4, 1), (1, 2) moves to (5, 2), and so on.