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krok68 [10]
3 years ago
8

Statements that are true for a cylinder with radius r and height h.

Mathematics
1 answer:
vampirchik [111]3 years ago
7 0

Answer:

Only the second and third statements are correct:

Doubling <em>r</em> quadruples the volume.

Doubling <em>h</em> doubles the volume.

Step-by-step explanation:

The volume of a cylinder is given by:

\displaystyle V=\pi r^2h

We can go through each statement and examine its validity.

Statement 1)

If the radius is doubled, our new radius is now 2<em>r</em>. Hence, our volume is:

\displaystyle V=\pi (2r)^2h=4\pi r^2h

So, compared to the old volume, the new volume is quadrupled the original volume.

Statement 1 is not correct.

Statement 2)

Using the previous reasonsing, Statement 2 is correct.

Statement 3)

If the height is doubled, our new height is now 2<em>h</em>. Hence, our volume is:

V=\pi r^2(2h)=2\pi r^2h

So, compared to the old volume, the new volume has been doubled.

Statement 3 is correct.

Statement 4)

Statement 4 is not correct using the previous reasonsing.

Statement 5)

Doubling the radius results in 2<em>r</em> and doubling the height results in 2<em>h</em>. Hence, the new volume is:

V=\pi (2r)^2(2h)=\pi (4r^2)(2h)=8\pi r^2h

So, compared to the old volume, the new volume is increased by eight-fold.

Statement 5 is not correct.

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I think i am right but I might not be hope this helps

5 0
3 years ago
Read 2 more answers
Someone help and please answer it fully
IRINA_888 [86]

Answer:

No, Matt did not solve the equation correctly

Correct Answer: x = 8

Step-by-step explanation:

4(x + 2) = 30

Step 1: Distribute

4x + 2 = 30      =>     This is his mistake, he should completely distribute 4    

                                  to x and 2

Step 2: Subtract 2 from both sides/Isolate x

4x = 28           =>      This part is done correctly, but wrong because of Step 1

Step 3: Divide both sides by 4

x = 7                =>      This is correct, but again, he messed up on Step 1

<h3>Let's find the correct answer to this equation:</h3><h3>4(x +2) = 30</h3>

Step 1: Distribute

Remember to distribute 4 to all terms in the parenthesis.

4(x + 2) = 4(x) + 4(2)

            = 4x + 8

4x + 8 = 30

Step 2: Subtract 8 from both sides/Isolate x

Move all the terms that do not belong to x to the other side. We can do this by subtracting 8 from both sides  => (opposite operation of adding 8)

4x + 8 = 30

4x = 30 - 8

4x = 32

Step 3: Divide both sides by 4/Isolate x

Now we want x by itself. Since x is being multiplied by 4, we have to use the opposite operation, dividing by 4, to have x on one side by itself

4x = 32

4(x) = 32

x = 32 ÷ 4

x = 8

-Chetan K

7 0
2 years ago
PLEASE HELP AND SHOW WORK!!
Nastasia [14]

Answer:

Pipe 1 alone fills a tank in 10 min

Pipe 2 alone fills the tank in 20 min

If both are turned on together, how long will it take to fill the tank???

Pipe 1 fills at the RATE of 1/10th tank per min

Pipe 2 fills at the RATE of 1/20th tank per min

Pipe 1 + Pipe 2 fills at the rate of 1/10+1/20 or 3/20th tank per min

Let x= time to fill the tank

(3/20)(x)=1 Where 1 denotes a full tank (Multiply both sides by 20)

3x=20

x=6 2/3 min----------both working together

NOW YOUR PROBLEM

Let x= amount of time for smaller pipe to fill the tank

Then (x-5)=amount of time for larger pipe to fill the tank

NOW HERE'S WHERE THE RECIPROCAL COMES IN:

The smaller pipe fills the tank at the RATE of 1/x cu units per min

The larger tank fills the tank at the RATE of 1/(x-5) cu units per min

Together, they fill the tank at the rate of 1/x+(1/(x-5)) cu units per min

But now we are told that together the fill the tank in 11 1/9 minutes. so our equation to solve is:

(1/x+(1/(x-5))(11 1/9)=1 where 1 denotes a full tank. In fact, in each of the above reciprocals, the 1 denotes a full tank.

So, dividing both sides by 11 1/9, we get:

1/x+(1/(x-5)=1/(11 1/9)-------------- which is your equation

I assume that you have no problems solviing this eq.

Hope this helps----ptaylor

Step-by-step explanation:

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