Answer:
dA/dt = k1(M-A) - k2(A)
Step-by-step explanation:
If M denote the total amount of the subject and A is the amount memorized, the amount that is left to be memorized is (M-A)
Then, we can write the sentence "the rate at which a subject is memorized is assumed to be proportional to the amount that is left to be memorized" as:
Rate Memorized = k1(M-A)
Where k1 is the constant of proportionality for the rate at which material is memorized.
At the same way, we can write the sentence: "the rate at which material is forgotten is proportional to the amount memorized" as:
Rate forgotten = k2(A)
Where k2 is the constant of proportionality for the rate at which material is forgotten.
Finally, the differential equation for the amount A(t) is equal to:
dA/dt = Rate Memorized - Rate Forgotten
dA/dt = k1(M-A) - k2(A)
Sarah needs 4.4 centimeters more to reach 5 feet before her next birthday.
The line integral along the given positively oriented curve is -216π. Using green's theorem, the required value is calculated.
<h3>What is green's theorem?</h3>
The theorem states that,

Where C is the curve.
<h3>Calculation:</h3>
The given line integral is

Where curve C is a circle x² + y² = 4;
Applying green's theorem,
P = 9y³; Q = -9x³
Then,



⇒ 
Since it is given that the curve is a circle i.e., x² + y² = 2², then changing the limits as
0 ≤ r ≤ 2; and 0 ≤ θ ≤ 2π
Then the integral becomes

⇒ 
⇒ 
⇒ 
⇒ 
⇒ ![-108[2\pi - 0]](https://tex.z-dn.net/?f=-108%5B2%5Cpi%20-%200%5D)
⇒ -216π
Therefore, the required value is -216π.
Learn more about green's theorem here:
brainly.com/question/23265902
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The answer is 3: 3+5+8=5+8+3