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guajiro [1.7K]
3 years ago
5

Help me plz!!!!! I have no ideia how to do this

Mathematics
1 answer:
BlackZzzverrR [31]3 years ago
4 0

Answer:

<h2>x² = -3</h2>

Step-by-step explanation:

In algebra, the goal is always to isolate the variable, so its value can be determined.

<h3>Step 1: Subtract 21</h3>

7x² = -21

<h3>Step 2: Divide by 7</h3>

x² = -3

<h3>Step 3: Check</h3>

7(-3) + 21 = 0

0 = 0 ✔

<h3>Step 4: Answer</h3>

x² = -3

I'm always happy to help :)

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3 years ago
The surface area of a cylinder is increasing at a rate of 9 pi square meters per hour. The height of the cylinder is fixed at 3
Alekssandra [29.7K]

Answer:

9\pi \text{ cubic meters per hour}

Step-by-step explanation:

Since, the surface area of a cylinder,

A= 2\pi r^2 + 2\pi rh  ................(1)

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h = height,

If A= 36\pi\text{ square meters}, h = 3\text{ meters}

36\pi = 2\pi r^2 + 2\pi r(3)

18 = r^2 + 3r

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r^2 + 6r - 3r - 18 = 0     ( by middle term splitting )

r(r+6)-3(r+6)=0

(r-3)(r+6)=0

By zero product property,

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Now, differentiating equation (1) with respect to t ( time ),

\frac{dA}{dt}= 4\pi r\frac{dr}{dt} +2\pi(r\frac{dh}{dt} + h\frac{dr}{dt})

∵ h = constant, ⇒ dh/dt = 0,

\frac{dA}{dt} = 4\pi r \frac{dr}{dt} +2\pi h \frac{dr}{dt}

We have, \frac{dA}{dt}=9\pi\text{ square meters per hour}, r = h = 3\text{ meters}

9\pi = 4\pi (3) \frac{dr}{dt}+2\pi (3)\frac{dr}{dt}

9\pi = (12\pi + 6\pi )\frac{dr}{dt}

9\pi = 18\pi \frac{dr}{dt}

\implies \frac{dr}{dt} =\frac{1}{2}\text{ meter per hour}

Now,

Volume of a cylinder,

V=\pi r^2 h

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\frac{dV}{dt}=\pi ( r^2 \frac{dh}{dt}+h(2r)\frac{dr}{dt})=\pi ((3)(6) (\frac{1}{2})) = 9\pi \text{ cubic meters per hour}

6 0
2 years ago
What is the range of this relation (3,2) (-3,0) (-4,0) (-2,4)
Sveta_85 [38]

Answer:

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3 years ago
Use function notation to write a recursive formula to represent the sequence: 3, 6, 9, …
dlinn [17]

Answer:

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OPTION 2: f(n) = f(n - 1) + 2

Substituting n = 1

f(1) = f(0) +  2 $ \ne $ 3.

So, this is eliminated.

Similarly, OPTION 3 and OPTION 4 can be eliminated as well.

4 0
3 years ago
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