Answer:
Correct option: fourth one -> y = 6(1/3)^x
Step-by-step explanation:
A decay curve is produced by an exponencial function with a rate lesser than 1 and greater than 0. This way, we have an exponencial function where the values of y decrease when the values of x increase.
The first equation is a linear equation.
The second and third equations are exponencial equations, but with a rate bigger than 1
The fourth equation is an exponencial equation with a rate lesser than 1 and greater than 0, so this equation will produce a decay curve.