Melody

921 Questions
34315 Answers

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Mathigon website

I just discovered a site called mathigon

https://mathigon.org/dashboard
read more ..

Melody Apr 2, 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. read more ..

Melody Mar 16, 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 read more ..

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Melody Mar 15, 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

off-topic

Melody Mar 13, 2022

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WELCOME BACK CPHILL !

Melody Feb 11, 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. read more ..

Melody Feb 1, 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 read more ..

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Melody Jan 9, 2022

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HAPPY BIRTHDAY CHRIS!

Melody Dec 20, 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 read more ..

off-topic

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Melody Nov 4, 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

off-topic

Melody Oct 29, 2021

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0

After one year you will owe $59000 * 1.1
After 2 years you will owe $59000 * 1.1 * 1.1

or using the formula

S = P * (1+i) ^ n
S = 59000 * 1.11 ^ 2
S = 72,693.90

MelodyOct 2, 2013

+118724

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I have worked it out via a commercial mathematics formula but maybe you have to do it using GP formula.
If you want me to work it out a different way let me know.
(Also, i often make careless mistakes so if you think that i am wrong you might be right. )

A=100000
i=10.5% = 0.105
n=25
R=yearly repayment

A = R * (a angle n at i)

(a angle n at i) = [1-(1+i)^(-n)] / i
=[1-1.105^(-25)] / 0.105
=8.739019 (4 dec places)
so
100000 = R * 8.739019
R = 100000 / 8.739019
= $11,442.93

MelodyOct 2, 2013

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I don't think that this question is complete. Are you sure the question is right?

MelodyOct 2, 2013

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10C8 * 0.72^8 * 0.28^2 = 0.2548 correct to 4 decimal places

MelodyOct 2, 2013

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You are right . It doesn't work on the web2.0calc.
This is a problem with this calculator.
I don't think that you should rely on this calc - it obviously has some problems.
It works fine on my casio calculator and also on my Sharp calculator.

The web2.0calc also gives a value to 5.5! Where there is no such value.
If you put this into my casio or my sharp calculator it gives an error message - which is what it is supposed to do.

In case you are not familiar with the symbol 5! (5 factorial) means 1*2*3*4*5 = 120 but 5.5! means nothing.

CONCLUSION
There are definitely bugs in the programming of the web2.0 calculator.

MelodyOct 2, 2013

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I'm not intending to do the question but these are the properties that your teacher is referring to. I copied them from http://www.aaamath.com/pro74ax2.htm

There are four mathematical properties which involve addition. The properties are the commutative, associative, additive identity and distributive properties.

Commutative property: When two numbers are added, the sum is the same regardless of the order of the addends. For example 4 + 2 = 2 + 4

Associative Property: When three or more numbers are added, the sum is the same regardless of the grouping of the addends. For example (2 + 3) + 4 = 2 + (3 + 4)

Additive Identity Property: The sum of any number and zero is the original number. For example 5 + 0 = 5.

Distributive property: The sum of two numbers times a third number is equal to the sum of each addend times the third number. For example 4 * (6 + 3) = 4*6 + 4*3

MelodyOct 2, 2013

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I have no idea what you are talking about.

MelodyOct 2, 2013

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1mm on the map = 62500mm in real life
so
175mm on the map = 62500mm * 175 in real life = 10937500mm
There are 1000mm in a metre so
10937500/1000 = 10937.5m
so X = 10937.5

alternatively

1mm on the map = 62500mm in real life = 62.5m
so
175mm on the map = 62.5m * 175 in real life = 10937.5mm
so X = 10937.5

MelodyOct 2, 2013

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You are very welcome!

MelodyOct 2, 2013

+118724

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4(x-4)+64=-2x

ok, get rid of the brackets first

4x-16 +64 = -2x

now add the like terms on the left (remember the minus sign belongs to the thing behind it, in this case 16) -16+64 = 64-16

4x + 48 = -2x

now you want the lots of x on one side and the numbers with no x on the other side If you take away 4x on the left side you will be left with just 48

4x-4x + 48 = -2x -4x
48= -6x
Now you need to get rid of -6 on the right side. The opposite of multiplying by -6 is dividing by -6. You have to do in to both sides.

48/(-6) = -6*x / -6
-8 = x

x = -8

You can check your answer LHS = 4(x-4)+64 = 4*(-8-4) +64 = 4 * -12 + 64 = -48 + 64 = 16
RHS = -2x = -2* -8 = 16
The left hand side equals the right hand side so the answer is correct.

MelodyOct 2, 2013