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+6252

Quote:
the 2 cylinders below are similar. cylinder A has a height that is half of cylinder B. The volume of cylinder A is 12 cubic inches. which is the closest to the volume of cylinder B ?

ok, cylinders can be described by two numbers, their radius and their height.

two cylinders are similar if for some number K>0 both the radius and height of one cylinder is K times those of the other.

the volume of a cylinder is V=pi R ² H

we are told that
H _A = (1/2) H _B
2*H _A = H _B

the cylinders are similar so
R _A = (1/2) R _B
2*R _A = R _B

Volume _B = pi R _B ² H _B =
pi (2 R _A) ² (2 H _A) = 8 pi R _A ² H _A =
8 Volume _A = 8 * 12 in ³ = 96 in ³

RomFeb 13, 2014

+118725

Bluegdog7:
13y^3+47y^2+13y+47

What do you want us to do with this, where is the question? I don't think that there are any integer factors if that is what you are after.

MelodyFeb 13, 2014

+118725

Kiki Riggs:
:( I need help with this .. the term # is 4 and it says add 15 subtract 10 each time ??

Your question does not make much sense.
If you add 15 and subtract 10 each time then you are really justs adding 5 each time arn't you?

MelodyFeb 13, 2014

Woops! You had the units right...it asked for miles. My bad--good on ya for stickin' the landing on those units! http://web2.0calc.com/questions/posting.php?mode=reply&f=2&t=8763#

GuestFeb 13, 2014

Not sure why they said

Quote:
Use 2
7
2
for π.

.....I just found the circumference and multiplied that by the amount of revolutions then found the decimal amount of the mile it had traveled. Long story short, I got the same answer...looks all good to me! 0.4 ft. sounds right! (Don't ever forget the units. ;P) Hope that helps!

GuestFeb 13, 2014

Quote:

wrong

GuestFeb 13, 2014

Okay, just remember, as afore mentioned, that the equation for the circumference of a circle is pi 2r and area is pi r^2

That being said, I suggest taking each question and finding the radius first, then the diameter by multiplying the radius by 2.

Let's do the first two!

13. C=49pi

Well, since we know that pi 2r is the circumference, we can logically see that 49 has to be the 2r part of the equation. Just divide 49 by two and....

Voilà! Your answer is 24.5 for the radius and 49 for the diameter.

14. A=81pi

We know that 81 has to be the radius squared because A= pi r^2

Thus, it isn't hard to sqrt. 81 and find that the radius is 9 and the diameter is 16 (double the radius).

I do hope this helps! Good luck.

GuestFeb 13, 2014

+6252

Quote:
What are the solutions of the equation x^2-3x-4=0

this one can be factored pretty easily by inspection

x ²-3x-4 = (x-4)(x+1)

so your solutions are x = 4 and x = -1

if you're no good with factoring by eye you can always use the trusty quadratic equation which says if

ax ² + bx + c = 0

then the solutions are given by

x = [size=200]([/size]-b +/- sqrt[size=150]([/size]b ² - 4ac[size=150])[/size][size=200])[/size][size=200]/[/size][size=150]([/size]2a[size=150])[/size]

in this case we've got a=1, b=(-3), c=(-4)

plugging and chugging we get

x = (3 +/- sqrt(9+16))/2 = (3 +/- 5)/2 = 8/2 and -2/2 = 4 and -1 which agree with what we've got above

RomFeb 13, 2014

+118725

Cool

BUT once is enough!

MelodyFeb 13, 2014

the answer is -purple degrees due to kinetic energy being a scalar and nutela tasting like the tears of pregnant mermaids.

GuestFeb 13, 2014

the answer is -purple degrees due to kinetic energy being a scalar and nutela tasting like the tears of pregnant mermaids.

GuestFeb 13, 2014

the answer is -purple degrees due to kinetic energy being a scalar and nutela tasting like the tears of pregnant mermaids.

GuestFeb 13, 2014

the answer is -purple degrees due to kinetic energy being a scalar and nutela tasting like the tears of pregnant mermaids.

GuestFeb 13, 2014

PPPPPPPPPPPPPOOOOOOOOOOOOOOOOOOOOOOOOOOOPPPPPPPPPPPPPPPPPPPPPPP! yum

GuestFeb 13, 2014

Eek! I forgot to mention that we have to find the diameter and radius! Those are the instructions.

And, yes, C= circumference and A= area.

GuestFeb 13, 2014

+6252

Quote:
These are the questions-
13. C=49pi
14. A= 81pi
15. C= 10pi
16. A= 25pi
17. C= 17pi
18. A= 9pi

I'm going to go out on a limb and guess that C is circumference and A is area.

let r be the radius of your circle
C = pi 2r
A = pi r ²

you should be able to figure these out now

RomFeb 13, 2014

+118725

Jay:
5/9+3/4x=2/3x-1/6x

Hi Jay and GrammarFascist,

That is a great answer there, I am impressed.
I would just do it a little bit diferently.
You have denominators of 9,4,3,6 (that's assuming all the x's are on the top)
now, the lowest common denominator of all these is 36.
If you multiply everything on both sides by 36 you will get rid of all the fractions in one fell swoop.
Then it will be much easier to deal with,

also,
Why don't you both join up properly,

There are some big benefits to joining up.
1) It is a little easier to make a post.
2) Once you have made a post you can edit it if you are a member. I edit my post all the time. I would hate not to be able to do that.
3) You can also delete your post so long as no-one has answered you yet.
4) No-one else can use your username
5) You can send and receive private messages to other people and make real friends. I know that I have.

---------------------------------------------------------------------------------------------------------------------------------

MelodyFeb 13, 2014

+6252

Quote:
ONE wrote::?: what could you say about the vectors 3c-d and 3/2d-1/2c

If c and d are linearly independent, then those vectors are also independent.

what vectors? are c and d vectors?

RomFeb 13, 2014

+118725

ncastleb:
What is the cube root of 27?

3 because 3x3x3=27

MelodyFeb 13, 2014

Feb 12, 2014

+118725

algebra2:
how to solve equations by using quadratic formula

I just did this one.

MelodyFeb 12, 2014

+118725

algebra2:
how to solve equations by using quadratic formula

It is only for the quadratic equations [they have an x ² term but no exponents (powers) higher than that] and they are equal to zero.

for example
5x ²-7x=12
I recognise that I can take all this to one side and have it equal to 0

5x ²-7x-12 = 0
Now that it is in the from

ax ² + bx + c = 0 I can use the quadratic formula
a=5, b=-7, and c=-12

Look at this you tube clip it will help you remember the quadratic formula.
Just high light it and then right clip, then choose goto from the drop down menu

http://www.youtube.com/watch?v=O8ezDEk3qCg

the for the substitution of your question
ALWAYS write the formula first then
x ={ - -7 ± sqrt[ (-7) ² - 4*5*-12 ] } / { 2 * 5 }

x = { 7 ± sqrt [ 49 + 240 ] } / 10

x = ( 7 ± sqrt [ 289 ] } / 10

The square root of 289 is 17. How is that for coincidence, I didn't do it on purpose

x = ( 7 ± 17 ) / 10

x = 24/10 OR x = -10/10

x = 2.4 or -1

If you substitute either of these values into the original equation it should make the equaation true. If not then I made a silly mistake somewhere.

Anyway I hope that helps. Make sure you look at the clip. That doesn't require much effort.

MelodyFeb 12, 2014

+6252

Einstein

The man revolutionized physics 100 or so years ago. You can at least spell his name correctly.

RomFeb 12, 2014

+6252

Quote:
a 30-kg girl and a 25-kg boy face each other on Friction-free roller blades. the girl pushes the boy, who moves away at a speed of 1m/s. what is the speed of the girl?

Momentum is conserved.

Before the push the total momentum of the boy and the girl is zero since they aren't moving.

After the push the boy has momentum of (25kg)(1m/s) = 25 kg*m/s

The girl must have momentum equal and opposite to this since their sum must remain zero.

(25 kg*m/s) = -(30kg)(v _girl m/s)

v _girl = -(25/30)m/s = -5/6 m/s where negative sign indicates the girl moves in the opposite direction from the boy.

RomFeb 12, 2014

Thanks.

GuestFeb 12, 2014

56.25/100=x/144

(cross multiply)
56.25*144 = 100x

x =0.5625*144 ft

GuestFeb 12, 2014

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