LOGARITHMS, CONIC SECTIONS, SEQUENCES
Evaluating an exponential function with base e that models a real...
The number of milligrams D (n) of a drug in a patient's bloodstream h hours after the drug is injected is modeled by the following function.
D(h) =40e-0.5h
Find the initial amount injected and the amount in the bloodstream after 7 hours.
Round your answers to the nearest hundredth as necessary.
Initial amount:
milligrams
Amount after 7 hours:
milligrams
X
5
?
Explanation
Check
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(a) 40 milligrams

(b)  1.21 milligrams

Step-by-step explanation:

Exponential Function

It's commonly used to model real situations in life, like this one proposed in the question where the number of milligrams of a drug D(h) in a patient's bloodstream h hours after the drug is injected is modeled by the following function.

(a) The initial amount injected to the patient can be found when h=0

Initial amount: 40 milligrams

(b) Let's plug h=7

D(7) =40e^{-0.5(7)}=40e^{-3.5}=1.21

The amount in the bloodstream after 7 hours is 1.21 milligrams

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

one set of data has more variation than the other. hope this !