Which function represents exponential decay? f(x)=1/2(2)xf(x)=3/4(-1/5)xf(x)=(7/ 2)xf(x)=2(2/3)x

The answer is (D)

Step-by-step explanation:  We are to select the correct function which represents exponential decay.

We know that an exponential decay is represented by the function with base less than 1.

For example, if we consider the following exponential function:

then f(x) will show exponential growth if b > 1 and exponential decay is b < 1.

Among the given functions, represents exponential decay, because the base is 0.66, which is less than 1.

Thus, (D)   is the correct option.

The graph of this resultant function is attached, which clearly represents exponential decay.

use this formula:

p(a\b) = p(a and b)/p(b).

take it from here.