Juan analyzes the amount of radioactive material remaining in a medical waste container over time. He writes the function f(x) = 10(0.98)x to represent the amount of radioactive material that will remain after x hours in the container.

Rounded to the nearest tenth, how much radioactive material will remain after 10 hours?

Question

Juan analyzes the amount of radioactive material remaining in a medical waste container over time. He writes the function f(x) = 10(0.98)x to represent the amount of radioactive material that will remain after x hours in the container. 

Rounded to the nearest tenth, how much radioactive material will remain after 10 hours?

kinged · Answer

Substitute 10 for x.

mathmale · Answer

For the sake of clarity (which can be all important in problem solving), please use the symbol   ^   to indicate exponentiation:

Incorrect:   f(x) = 10(0.98)x
correct:       f(x) = 10(0.98)^x, or

mathmale · Answer

$$f(x) = 10(0.98)^x$$

mathmale · Answer

Since the quantity inside parentheses, 0.98, is less than 1, the function f(x) is decreasing.  I agree that you need only substitute 10 for x in this equation and then evaluate the result.