All Answers

+118725

Beth909:
How many different committees can be formed from 7 teachers and 9 students if the committee is to consist of 3 teachers and 4 students?

7C3 * 9C4

MelodyDec 10, 2013

+118725

michael:
Taru and Reiko simultaneously grab a 1.61 kg piece of rope and begin tugging on it in opposite directions. If Taru pulls with a force of 18.0 N and the rope accelerates away from her at 1.24 m/s2, with what force is Reiko pulling? Round your answer to 2 decimal places.

force=mass*acc = 1.61 * 1.24 = 1.9964N
But the force in the other direction has to be counteracted so
Rieko must be pulling with a force of 18+1.9964 = 19.9964N => 20.00N

MelodyDec 10, 2013

+118725

trueskawa:
3.7 x10 to the power of -14 Joules= M(mass) x 3.0 x 10 to the power of 8 per meter. Find the mass
According to Einstein’s equation, what mass is equivalent to an energy of
3.7 × 10to the power of –14 J?
You should use a value for c of 3.0 × 10 to the power of 8 m s–1 and give your answer in kilograms, in scientific notation and to two significant figures.

I think that you forgot that c is squared.
e=mc ²

3.7 * 10 ^-14 = M * (3 * 10 ⁸) ²

3.7 * 10 ^-14 = M * (9 * 10 ¹⁶)

(3.7/9) * (10 ^-14 / 10 ¹⁶) = M

0.411111 * 10 ^-30 = M

M = 4.11111 * 10 ^-31

M = 4.1 * 10 ^-31 Kg (to 2 significant figures)

MelodyDec 10, 2013

127

GuestDec 10, 2013

So i think you're trying to say, from a given angle (lets call it X) the adjacent side is 4.870 inches and the opposite side is 3.900 inches. What is the angle?
So if that is indeed your question this is a TanX formula. TanX = opposite/adjacent. So TanX = 4.870/3.900 or about 1.249.
Now X does not equal 1.249. TanX = 1.249. Then do the inverse Tan (or Tan^-1) of 1.249 on a trig calculator (or if you're retro, use the back of an old trig textbook) and you get 51.3 degrees (or .896 radians)

GuestDec 10, 2013

+118725

JETTEBOW:
what the sum of 21(2-X)+12x=44

First tidy up the left hand side, you will have to expand the bracket and collect the like terms
next you will have to get all the numbers that don't have an x off the left side and the you are nearly finished.
Can you do it then?

If you need more help post again

If this presents big problems maybe you should watch some you tube clips on solving equations
Here is one of them
http://www.youtube.com/watch?v=p5e5mf_G3FI

MelodyDec 10, 2013

+118725

tasneemcat@aol.com:
what is the rearrangement of the equation v=d/t so t is at the start

Start by multiplying both sides by t that will get rid of the fraction and then think about what you need to get rid of next.

MelodyDec 10, 2013

+118725

Warren:
3cos2(x)=3sin^2+2

Your question soesn't really make sense Warren
do you mean this?
3cos(2x)=3sin ²(x)+2

MelodyDec 10, 2013

+118725

southdakota:
the algebra question is asking me to solve for x

9^x-1=4

Can you start it?
You will get to a point where 9^x = some number

Whenever you need to find the value of an exponent, you have to take the log of both sides.
Then you will need to use one of the log identities on this page to help solve it.
http://en.wikipedia.org/wiki/List_of_logarithmic_identities

Have a go it it from here.

MelodyDec 10, 2013

+118725

mathmathmath:
the problem is:

Find the time required for money invested at an annual rate of 4% to double in value if the investment is compounded continuously. Round to the nearest hundredth of a year.

please help

You have to give the initial amount of money a value. It doesn't matter how much because $5 will double in the same amount of time as $1000 will double.
I'm going to start with $1 because it is easiest and I need to work out how long it will be before I have $2.

Inially I have $1
After one year I have $1*1.04 = 1.04 (dollars)
After 2 years I have 1.04*1.04 = 1.04 ²
After 3 years I have 1.04 ²*1.04 = 1.04 ³

After n years I have 1.04 ⁿ dollars
The answer will be given by the equation

2=1.04 ⁿ
Since it is the exponent that you need to find, you wil need to take the log of both sides to get the answer.

Try to finish it by yourself.

MelodyDec 10, 2013

+118725

San Takisojotando:
pai che no do se qui pu ti na di ti cu o xi zen mai do na. Chu ce nu te qi on nu pe jo ma vug xin zep po?

234(23*12) x/12=?

Hi Lmao, I don't understand your words but this is the answer to your question. The 12's cancel out.

= 234*23*12*x / 12
= 234*23x / 1
=5382x

I tried to translate this.
One translator said it was Gallacian
the other said it was Romanian
Neither translation made any sense.

Can anyone on the forum tell me what language this is, or what Lmao is trying to explain?

MelodyDec 10, 2013

+118725

jimmy:
what percentage is 20,000 of 550,000

you write it as a fraction first.
then you multiply by 100 to turn it into a percentage (don't forget the percent sign)

MelodyDec 10, 2013

+118725

StuckWithMath:
I'm currently stuck with my college math. i hate to do this but i need help with four questions

A. SOLVE FOR X

log(4)x+log(4)(x-15)=2

B. SOLVE FOR X

ln(x+1)=0

C. SOLVE FOR X

9^(x+1)=4

D. SOLVE FOR X

(3-2x)-4(2+x)=4x

There is a lot of questions here.
ok I'll start with d.
(3-2x)-4(2+x)=4x
expand out the left hand side and simplify it by adding like terms.
move the 'lots of x' to the right side - do you know how to do that? (remember it is opposite so if it was +20x then you would -20x from both sides.)
lastly you divide both sides by the number in front of the x.

question C you have to take the log of both sides to solve it.
then look for an identity you can use from this web page
http://en.wikipedia.org/wiki/List_of_logarithmic_identities

question B consider this
log _xy = 0
then x ⁰ = y
what does y have to equal?
This is an interactive web page that takes an introductory look at logs. You probably should work through it.

question A is the hardest one
log(4)x+log(4)(x-15)=2
If you mean exactly what you have written then the question is
xlog4 + (x-15)log4 = 2
You can collect the lots of log 4 on the left eg 6x + (3+1)x = (6+3+1)x This is just an example to give you a hint.
Then you can solve it like any equation. Just remember log4 is just a number.

That's enough help for starters.
Get back to me and show me what you have acheived by yourself.

MelodyDec 10, 2013

+118725

Guest:
:geek: In Fraction form, what is 28 divided by 26

Well, how many times does 26 go into 28?
Or to put it a different way
If you have 28 lollies and you divide them amoung a class of 26 students, How many whole lollies does each child get?
The answer is the whole number part.

How many are left over? The left over number goes over the number you divided by to get the fraction part.

Now you can simplify the fraction bit by dividing the top and bottom by 2.

You try to do it and post your answer so that I can see it.

MelodyDec 10, 2013

+118725

lynda:
Explain why y\this works. Assume the person is working 40 hours a week.

Explain why what works?

MelodyDec 10, 2013

+118725

2a+2b

Is this a question?

MelodyDec 10, 2013

+118725

Hi Professor Lopez,
You have differentiated the function correctly but you have not stated the domain.
-------------------------------------------------------------------------------------
Give the Domain of the function g(x)=1/x

Hello 'Hello'
Do you know what a domain is?
It is all the values that x can be, does that help?
What you really need to do is think about what x cannot be first.

You try to answer this, what can x NOT be?
Then try to write the domain which is what x can be.
come back to me with your answer.

MelodyDec 10, 2013

Dec 9, 2013

+118725

clk2013:
if ln e = 1, then ln e^2 = ?

I want you to look at at a different question first.
x = log ₂8
I can write this a different way
8 = 2 ^x
so x must be 3 because 2*2*2=2 ³=8

Remember, a logarithm (log) is a power (or exponent)

so if
x = log ₂(8 ⁴)
(8 ⁴) = 2 ^x
(2 ³) ⁴ = 2 ^x

2 ^(3*4) = 2 ^x

3*4 = x
x=12

Now lets see if we can do this more quickly.
We know that log ₂8 = 3
so
log ₂(8 ⁴) = 4 * log ₂8 = 4*3 = 12

the general rule is
log _b(x ^d) = d * log _bx

This is a page of logarithmic identities
http://en.wikipedia.org/wiki/List_of_logarithmic_identities ( you might like to bookmark this webpage )

also, your question tells you that lne=1 but you should really know this yourself
ln means log _e (log base e)
lets consider
y=log _ee
I can rearrange this to
e = e ^y
e ¹ = e ^y
y=1
that is why lne=1

You should be able to do your own question now.

MelodyDec 9, 2013

+118725

Jon:
What percentage of 4.54 billion years is 213 years?

http://www.oxforddictionaries.com/words/how-many-is-a-billion

I have a problem with this questionn because a billion is a different number in different countries
In the US it is 1 000 000 000 which is 1000 million or 10 ⁹
In the UK and Australia I it is 1 000 000 000 000 which is a million million or 10 ¹²

Web2.0calc seems to be based in the US so I will use their billion.
First you write your number as a fraction

213 / (4.54 x 10 ⁹)

then, if you want to turn it into a percent, just multiply by 100 and put the % sign.

213 / (4.54 x 10 ⁹) x 100%

MelodyDec 9, 2013

+118725

Theresa21T:
e^-247
I'm not sure how to put it into my calculator because when I do it get 0, but the answer on the assignment is 5x10^-108. Any one know?