Which statements are true about exponential decay functions? check all that apply. a. the domain is all real numbers. b. as the input increases, the output increases. c. the graph is the same as that of an exponential growth function. d. the base must be less than 1 and greater than 0. e. the function has a constant multiplicative rate of change.

Exponential decay is described as when the quantity of any entity decreases in accordance with the entity's present value. For example - if a group of population decreases and the decreasing rate value is proportional to the size of the population.

So, the correct options are :

A. The domain is all real numbers. (the function is always defined for real values)

D. The base must be less than 1 and greater than 0.  

E. The function has a constant multiplicative rate of change.

70 years.

step-by-step explanation:

answer: 8 years

step-by-step explanation:

the explanation is that in 8 years the child will be 20 and in 8 years the father will be 40 and 20 is half of 40.