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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2/3 times 3

Draw some cakes. divide them all into thirds.
Colour in 2/3 of a cake 3 times. Don't start on a new cake until all of the current cake is coloured. See how much cake/s you end up colouring.

After you have done this think about how you could have got the answer just with the numbers.

You can of course use your calculator to check the answer.

MelodyNov 2, 2013

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"find the angular size of a circular object with a 1 inch diameter viewed from a distance of 2 yards"

I am assuming the simplest scenario.
Your body and the circle are in parallel planes. Your eye to the centre of the circle are at right angles to those planes.

start by considering an isosceles triangle, the circle diameter is one side (1 inch ), the other 2 equal sides mean at the centre of your eye.
Cut the isosceles triangle in half to make 2 right angled triangles.
Now the centre side is 2 yards = 72 inches long and each little side is 0.5 inch long.

Now use trigonometry to get half the required angle (that is, the little angle in one of the right angled triangles)
then duble it to get the whole angle.

Draw a picture to try and work out what I am saying. if you still need help post again and I will try to explain more.

MelodyNov 2, 2013

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I think you mean

trying to figure out what the tax on a chair is the chair is 178.90 and the tax rate is 5.75%

Different countries do this differently and I don't know your countries system so I will assume
you pay $178.90 plus tax

tax = 5.75/100*178.90

MelodyNov 2, 2013

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5X ² - X - 2 = 4X ²

then solve this question by using log both sides, right??

NO not right.
now you take it all to one side and solve it as quadratic equation.

MelodyNov 2, 2013

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to find the time it takes for a dropped object to hit the ground, you can use the equation, h=16t^2, where h, is the height in feet and t, is the time , in seconds. if an object is dropped from 48 feet, what is the approximate falling time, in seconds, of this object.

just substitute h=48 and solve for t

MelodyNov 1, 2013

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x-(0.44x) = 0.1369
x - 0.44x = 0.1369
x ( 1- 0.44) = 0.1369
can you do it from here?

MelodyNov 1, 2013

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this question has received an enormous amount of attention in the second forum is anyone is interested.

MelodyNov 1, 2013

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A cottage factory with 178 workers computed its mean wage bill and found it to be K£ 49.95 and its modal wage was K£ 44.50. If the variance was 78.5625, calculate;
i. The total wage bill 178*49.95
ii. The median wage I don't think that there is enough information given
iii. The coefficient of variation sqr(78.5625) / 49.95

"The coefficient of variation represents the ratio of the standard deviation to the mean, and it is a useful statistic for comparing the degree of variation from one data series to another, even if the means are drastically different from each other."

MelodyNov 1, 2013

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http://en.wikipedia.org/wiki/L'H%C3%B4pital's_rule

Use L'Hopital's Rule

This is not exactly the question you wrote, but I think it is what you intended.
If I got the intention wrong then I am sorry.

lim [x ² + x ³ - x] / [x ⁴ - x ² +1]
x--> infinity

= lim [2x + 3x ² - 1] / [4x ³ - 2x]
x--> infinity

= lim [2 + 6x ] / [12x ² - 2 ]
x--> infinity

= lim 6/(24x)
x--> infinity

=0

MelodyNov 1, 2013

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log ₂ (5X ² - X - 2 ) = 2 + 2 log ₂ X
First I am going to assume that this is the question that you intended.

Now I am going to look at the RHS

RHS= 2 + 2 log ₂X
=2(1+log ₂X)
=2( log ₂2 + log ₂X)
=2 log ₂(2X)
= log ₂(2X) ²
=log ₂(4X ²)

So 5X ² - X - 2 = 4X ²

Now you should be able to solve it yourself.

MelodyNov 1, 2013