Melody

921 Questions
34316 Answers

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Mathigon website

I just discovered a site called mathigon

https://mathigon.org/dashboard
lire plus ..

Melody 2 avr. 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. lire plus ..

Melody 16 mars 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 lire plus ..

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Melody 15 mars 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

Hors sujet

Melody 13 mars 2022

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WELCOME BACK CPHILL !

Melody 11 févr. 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. lire plus ..

Melody 1 févr. 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 lire plus ..

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Melody 9 janv. 2022

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HAPPY BIRTHDAY CHRIS!

Melody 20 déc. 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 lire plus ..

Hors sujet

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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

Hors sujet

Melody 29 oct. 2021

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http://www.youtube.com/watch?v=QV9k6dRQQe4

Maybe you would be interested in this video.

(Although I will admit that it didn't do much for me)

Melody22 nov. 2013

+118730

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In right ∆ABC, C is a right angle and sin A =243/312 . What is mB?

Is m the midpoint of CA?

If it is then I would use pythagoras oto find AC
then i'd halve it to find Cm
then Id use pythagoras to find mB

Melody22 nov. 2013

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not if the numbers are 1/2 and 0.4

Melody22 nov. 2013

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How did my teacher got that if sin α=0.4, α=23.58 degrees? All I am getting is sin(0.4)=0.006981260298

The way you are doing it 0.4 is the number of degrees and 0.0069etc is the sin of 0.4 degrees.
That is NOT the question

sin (alpha )= 0.4
0.4 is the sine of the angle - not the angle itself.

You need the Inverse sin of 0.4 to get the angle. Written sin ^-10.4
[do not confuse this with a power of -1]
This can also be called arc sin 0.4 or asin0.4

Anyway on your calculator press

shift sin 0.4 = and you will have your teacher's correct answer
If you then press the degress minutes and second button it will convert it for you int degrees minutes and seconds.

Melody22 nov. 2013

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2:3
4:6
1:1.5
200:300
0.2:0.3
10x:15x

how many more do you want?

Melody22 nov. 2013

+118730

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Given the function g(x)=2x-3 and h(x)=4x, find the value of x if hg(x)= 1/2g(x)

your question is ambiguous
do you mean
h(x)g(x)= 1/2g(x) ?
in which case it is just h(x)=1/2 etc
or do you mean
h(g(x))= 1/2g(x) ? which I don't think is doable. because it gives you 4=1/2

Melody22 nov. 2013

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(2a+3b-c)-(4a-5b+2c)

I'd suggest that you get rid of the brackets first, which I know is what guest just said.
I'd just look at it a bit differently

There is an invisable 1 between the minus sign and the second bracket - put that in and you have

(2a+3b-c) -1 (4a-5b+2c)
now expand the second bracket by mulltiplying everything by -1 and you get
(2a+3b-c) -4a +5b - 2c
Just like guest said - when multiplying by -1 all the signs inside the bracket swap.
tThe first brack has always been unnecessary
so you have

2a+3b-c -4a +5b - 2c
now you can just collect like terms.

Melody22 nov. 2013

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How do you factor out 500000e^0.068-0.05(500000e^0.068)? It's suppose to give me a term that's the difference of two numbers and it's supposedly suppose to be easy to calculate (the difference).

Just factorise out 500000e^0.068 don't do anything else first. The answer comes very easily from there. There will of course be an e in the answer.

Melody22 nov. 2013

+118730

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x^3/2
---------
x^5/3

The correct answer to is (x^5/6) all over x.
However when I do I just get a 1/x^1/6, Anyone care to explain?

Your answer is correct but it you multiply your answer top and bottom by x^(5/6) you will get the other answer.

Your answer is the better more simple one.

Melody21 nov. 2013

+118730

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e^(x^2)=84

ln {e^(x^2)} = ln 84

x^2 ln(e) = ln 84

x^2 = ln84

x = +- sqrt(ln84)

Melody21 nov. 2013