When a<0, the graph of y=ab^x is reflected in the x-axis.
B
Practice makes perfect
We can see that there is a minus sign in front of the given exponential function.
y= - 2(0.5)^xThe graph of the above function is the graph of f(x)=2(0.5)^x reflected in the x-axis. To draw it, some points on the graph of f can be reflected first. The y-intercept of the graph of f(x), for example, is reflected to the point (0,- 2).
(0,2) Reflect in thex-axis ⟶ (0,- 2)
This point will be the y-intercept of the graph of y=- 2(0.5)^x.
Therefore, the graph in B matches with the function y=- 2(0.5)^x.
Extra
Graphing Exponential Functions
When we draw an exponential function y=ab^x, the value of a and b changes the shape of the graph. The graphs below show the possible graphs of the exponential functions.
