When a<0, the graph of y=ab^x is reflected in the xaxis.
D
Practice makes perfect
We see that there is a minus sign in front of the function.
f(x)= - 2(2)^xThe graph of the above function is the graph of y=2(2)^x reflected in the x-axis. To draw it, some points on the graph of y=2(2)^x can be reflected first. The y-intercept of the graph of y=2(2)^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 f(x)=- 2(2)^x.
Therefore, the graph in D matches with the function f(x)=- 2(2)^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.
