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frozen [14]
3 years ago
5

Let A be the area of a circle with radius r. If dr/dt=3, find dA/dt when r=2.

Mathematics
2 answers:
zlopas [31]3 years ago
5 0
Area=pir^2
take deritivive
dA/dt=2pir (dr/dt)
given dr/dt=3
dA/dt=2pi(2)(3)
dA/dt=12pi

astraxan [27]3 years ago
3 0
\bf \textit{area of a circle}=A=\pi r^2
\\\\\\
\cfrac{dA}{dt}=\pi \cdot 2r^1\cdot \cfrac{dr}{dt}\implies \cfrac{dA}{dt}=\pi \cdot 2r\cdot \cfrac{dr}{dt}\quad 
\begin{cases}
r=2\\
\frac{dr}{dt}=3
\end{cases}
\\\\\\
\cfrac{dA}{dt}=\pi \cdot 2(2)(3)
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$6000 invested at an APR a 4.4% for 20 years what is the balance in the account after 20 years
butalik [34]

Answer:

The balance in the account after 20 years will be $11280.

Step-by-step explanation:

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The simple interest formula is given by:

E = P*I*t

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After t years, the total amount of money is:

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In this problem

We want to find T, when P = 6000, I = 0.044, t = 20

The first step is find the earnings due to interest. So

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6 0
3 years ago
Jack crawled 4 ft and Christine crawled 3⁄4 the distance Jack crawled. If you add the distance they each crawled together, what
stepan [7]
Before going into the details of the problem, let us first write down the most important information required for solving this problem.
1 ft = 12 inches
The distance that was crawled by Jack = 4 ft
                                                                = (4 * 12) inches
                                                                = 48 inches
The distance crawled by Christine = 3/4 of the distance crawled by Jack
                                                         = (3/4) * 48 inches
                                                         = 3 * 12 inches
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Then
The total distance crawled by the two children's = (48 + 36) inches
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So Jack and Christine together crawled a distance of 84 inches.

8 0
3 years ago
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tensa zangetsu [6.8K]

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Step-by-step explanation:

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8 0
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