Member: Melody

921 Questions
34315 Answers

1742

+118725

Mathigon website

I just discovered a site called mathigon

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

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Melody Apr 2, 2022

-8

609

+118725

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 ..

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Melody Mar 16, 2022

-2

1459

+118725

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

-3

871

+118725

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

WELCOME BACK CPHILL !

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Melody Feb 11, 2022

-5

717

+118725

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 ..

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Melody Feb 1, 2022

-7

889

+118725

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

-6

996

+118725

HAPPY BIRTHDAY CHRIS!

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

-9

1091

+118725

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

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Melody Oct 29, 2021

+118725

JamesJonez:
I have a 25% chance to succesfully finish a task. What is the chance of it failing 9 times in a row?

The chance of failing once is 75% = 0.75

the chance of failing 9 times in a row is (0.75) ⁹

MelodyApr 4, 2014

+118725

ERS:
least common multiple of 9and 6

the multiples of 9 are 9, 18, 27, 36, 45, 54,.....

The multiples of 6 are 6, 12, 18, 24, 30, 36, 42, 48,........

The least common multiple is the smallest number that is in both lists.

MelodyApr 4, 2014

+118725

Hi Mic,
You could take a look at this thread. It may well be useful to you.

http://web2.0calc.com/questions/negative-exponents-negative-indices

MelodyApr 4, 2014

+118725

Hi Stu,
Ok I'll do some examples maybe that will help

Say you want to differentiate
1) y = x ⁷
dy/dx = 7x ^7-1 = 7x ⁶
This is a formula for the gradient of the tangent.
If you want to know what the gradient of the tangent is when x=2 you would substitute in x=2 in and get dy/dx = 7 * 2 ⁶ = 448 (at x=2)

2) y = 9x ¹²

You bring the power down the front and multiply it by any coefficient that is already there -> put the x -> then drop the power down by one.
dy/dx = 12*9x ¹¹
dy/dx = 108x ¹¹
If you want to know the gradient of the tangent at the point (1,9) then you will have to substitute x=1 into the derivative formula. dy/dx = 108 [at (1,9)}
It is always the x value that you sub in.

I'll show you how you can use different notation. I know that they have been confusing you.

3) d/dx 5x ⁴ = 20x ³

4) f(x) = -4x ³
f '(x) = -12x ²

5) y = 7x ^-2
y' = -14x ^-3
In this case y' is a short cut notation for dy/dx

NOW If there are a lot of terms ADDED or SUBTRACTED together you can just do each one individually.

6)y = 3x ⁵ - 4x ² + 9x + 23

dy/dx = 5*3x ^5-1 - 2*4x ^2-1 + 9 + 0

dydx = 15x ⁴ - 8x ¹ + 9

dy/dx = 15x ⁴ - 8x + 9

7) y=mx+c
dy/dx = m because x has a power of 1 and 1-1=0 and x ⁰=1
also remember that I told you the derivative gives you the gradient of the tangent to a curve. A straight line always has the same gradient. It is m.

8) d/dx ( nx ³-nx ²+c ) = 3nx ² - (n-1)x ¹ + 0 => 3nx ² - (n-1)x

I hope that this helps.

MelodyApr 3, 2014

+118725

140403 factor tree.JPG

MelodyApr 3, 2014

+118725

help me:
(c^5a/c^4a)^1

This question is open to interpretation

[size=150]It is really
[ (c ⁵*a/c ⁴) * a ] ¹= ca ²
[/size]
But I think this may be what you meant.

140403 indices.JPG

MelodyApr 3, 2014

+118725

Thank you Alan

MelodyApr 3, 2014

+118725

sol96:
:geek: what is 468.72÷93

Same answer as last time.

MelodyApr 3, 2014

+118725

sol96:
what is 93÷468.72

There is a calculator on the site if yours is broken.

MelodyApr 3, 2014

+118725

Deleted

MelodyApr 3, 2014

Username	Melody
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