Melody

921 Questions
34315 Answers

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Mathigon website

I just discovered a site called mathigon

https://mathigon.org/dashboard
lee mas ..

Melody 2 abr 2022

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Reporting problems.

There are a number of people having problems at the moment.
If you lodge an error can you please give all relevant information that you can think of.
Where you are in the world - the city or the country - is often very important information. lee mas ..

Melody 16 mar 2022

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How to make an empty rectangle in Latex

I just worked out how to make an empty box of various horizonal size easily in LaTex.
This is not a recommended method, but other methods that I have tried here have not worked.
This coding is really simple. Just put letters inside lee mas ..

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Melody 15 mar 2022

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HAPPY ANNIVERSARY CHRIS! (CPhill)

I just realized that you became a member here exactly 8 years ago today!

It has been great to have you here all that time

Fuera tema

Melody 13 mar 2022

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WELCOME BACK CPHILL !

Melody 11 feb 2022

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Very interesting question. No high level maths required.

This question was posted a couple of days ago.
https://web2.0calc.com/questions/geometry_73561

I think it is really interesting. It looks much more difficult than it really needs to be. lee mas ..

Melody 1 feb 2022

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Members have a better experience. Their questions get more attention.

Almost everyone is posting as a guest.
If you post as a member your questions will have a far greater chance of a timely and helpful response.
If you are a genuine learner and interact with us, you will become known and answerers will do lee mas ..

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Melody 9 ene 2022

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HAPPY BIRTHDAY CHRIS!

Melody 20 dic 2021

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Some guidelines for question askers.

Please note:
1) Ask only one question per post.
2) When asking a question talk about what you have tried for yourself. Then people will take you more seriously and will be more able and willing to help.
3) If you get an answer lee mas ..

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Melody 4 nov 2021

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Remeniscing - a little historical humour.

I just found this old post that some of you, who have been around for a while, might find amusing.

https://web2.0calc.com/questions/look-at-the-new-leader-board

Fuera tema

Melody 29 oct 2021

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0

SubDivision:
What is (-5x^5 + 7x^4 -5x^3 + 8x^2 + 2x + 9) + (-8x^5 -5x^4 + 8x^3 + x^2 -9x + 2) =

Hi SubDivision
Do you think those brackets serve any purpose or can they just be removed?

Just add the like terms.
terms that are like, have the same letters (pronumerals) and each pronumeral must be raised to the same power.
In this question, the only pronumeral is x
If there are 2 terms where x is raised to the same power (exponent), they can be combined with addition or subtraction.
And, that is all that you can do in this question.

If you want to you can post back with your answer, or your attempt at an answer. And I'll help more.

Happy calculations!

Melody10 dic 2013

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hi dsa,
I think that you should check that answer
and
asd,
if that is the type of answer that you want then you need to put the word factorise in your question.

Melody10 dic 2013

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Melissa:
Oh my gosh, I messed it up again... I think.

I think I should make the formula : 150= 80e^-(k)(1) +82

Newton's law of heating and cooling. I'm so lost.. Thank you for the help!

T(t) = A + B e ^-kt

T(1) = 82 + 80e ^-kt

150 = 82 + 80 e ^-k

Now I have got it to your starting point
surely you can at least start this Melissa
Can't you get e ^-k on one side by itself ?
After you do that then you will need to take the log (base e is best for this problem) of both sides. You always have to do this when the unknown is an exponent.
If you need to look up log identities, this is a good place
http://en.wikipedia.org/wiki/List_of_logarithmic_identities

Have a go and if you get stuck, post again.

Melody10 dic 2013

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8th Grade student:
I don't know anything about scientific notation, I get everything about exponents up to there...can someone please explain how scientific notation works, and what is a good way to transfer from standard notation to scientific notation? Thanks in advance.

I found a good you tube video for you

http://www.youtube.com/watch?v=Dme-G4rc6NI

The only thing that I would like to add to what Tyler is telling you is that if the number is big (10 or bigger ) then the power is positive
If the number is little, less than 1 then the power is negative.

Tyler talks about moving the point left or right. I think it is easier just to think about whether it is a little number or a big number.

anyway, the clip should help you a lot.

i do think the way he talks about moving the point is a bit confusing.
If you are changing a number from scientific notation to standard notation
you have to move the decimal point the number of places shown by the exponent.
if the exponent is positive you go in the direction to make the number bigger.
if the exponent is negative you go in the direction to make the number smaller.

Melody10 dic 2013

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Melissa:
how to solve for k?
150=80e^(-k)(0)+82

Hi Melissa,

I am not quit sure where you want me to put the 0 but no matter where I put it the question does not make sense.
One way I get 150=82 and the other way I get 150=162

I think you better check the question.

Melody10 dic 2013

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Kat:
An old watch had a 1 year warranty; the new model watch has a 2 year warranty. What is the percent increase in the length of the warranty?

The fraction increase is [the increase in warranty / the original warranty]

to turn it into a percent you multiply this answer by 100 and put a percent sign.

Melody10 dic 2013

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iamnino:
Differentiate the following functions with respect to x:

y = ln7x

I suspect that you mean y=ln(7x)

Now if y=ln[f(x)]
then
y' = f '(x) / f(x)

You can do it now can't you?

Melody10 dic 2013

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Fearthemonkey:
what is (2x^4/3)^3? Please help

(2x ^(4/3)) ³

okay you are going to have to use a few indices rules for this one

(x ^m) ⁿ = x ^(mn)

(ab) ^m = a ^m*b ^m

I think that is all you really need

can you have a go at it yourself now?

And by the way, you have an great username!

Melody10 dic 2013

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Dovepaw:
10 ft 7 in. = _______ in?

there are 12 inches in a foot so 10feet = 10*12 inches

so the answer must be

10*12 + 7 inches

Melody10 dic 2013

+118690

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Anon Help:
What is Cos(20) = 60/R ?

Multiply both sides by R to get R off th bottom
then divide both sides by Cos20 to get R by itself
then do it on your calculator.

Melody10 dic 2013