Which graph models the function f(x)=-2(3)^x

Solution:
[tex]\text{Given: }f(x)=-2(3)^x[/tex]
We are an exponential function.
[tex]y=ab^x[/tex]
If a<0 and b>1 then graph is decreasing.
If a>0 and b<1 then graph is decreasing.
If a<0 and b<1 then graph is increasing.
If a>0 and b>1 then graph is increasing.
[tex]\text{We have a function }f(x)=-2(3)^x[/tex]
Here a=-2<0 and b=3>1 therefore, f(x) is decreasing.
Horizontal asymptote , y=0
x-intercept: Doesn't not exist
y-intercept: (0,-2)
Using above information we will draw the graph f(x)
We make table of x and y for different value of x
x y
-2 -0.22
-1 -0.67
0 -2
1 -6
2 -18
Plot these points on graph and join the points.
Please see the attachment to see the graph.
Answer:
Reflection across x-axis:
[tex](x, y) \rightarrow (x, -y)[/tex]
Vertically stretch:
A function y=a f(x) is vertically stretch by a factor a > 1 is that of parent function y=f(x)
Given the graph: [tex]f(x) = -2(3)^x[/tex]
We will make a table values for a few values of x.
then we will graph the given function.
x f(x)
-2 -0.2222..
-1 -0.6666..
0 -2
1 -6
2 -18
3 -54
Note that as x increases, f(x) decreases
Now, using these points (-2, -0.2222..), (-1, -0.666..), (0, -2), (1, -6) , (2, -18) and (3, -54)
Plot the graph of the given function as shown below:
We observe that the curve is that of [tex]f(x) =(3)^x[/tex] except it is vertically stretch by a factor 2 and reflection across x-axis.