The half life of a certain radioactive material is 68 hours an initial amount of the material has mass of 641 kg. write an exponential function that models the decay of this material. find how much radioactive material remains after 4 hours. round your answer to the nearest thousandth

a)

b) Radioactive material remain after 4 years = 615.39 kg

Step-by-step explanation:

we know that the general equation of exponential decay is:

where,

A is amount after time t

P is the initial amount =641 kg

k is a constant

t is time  period

The half-life of a certain radioactive material = 68 hours

The required equation will be :

For t=4 years

Radioactive material remain after 4 years = 615.39 kg

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10