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

+118725

+3

MelodyJan 30, 2014

+118725

+17

I believe that is it for the night. I have not checked every question, if you are not happy with your reply bump your question up with a comment about why you are doing so.

Great answers were given by guest, reinout-g, halper, I like Serena, Anonymous4338, Zamaronics, DavidQD, Rom and Kitty<3.
Rom only became a member today. We hope you enjoy your experience with us.

Reinout-g posted 2 really good puzzles. One he called Logic's puzzle. It had me stumped but a great answer came from theiswe.
reinout-g has also posted a new number puzzle. I normally do these very easily but this one appears to me to be very difficult.

Please join up if you haven't done so already
I know that some people, even some core people are not formally members.
There are some big benefits to joining up.
1) It is a little easier to make a post.
2) Once you have made a post you can edit it if you are a member. I edit my post all the time. I would hate not to be able to do that.
3) You can also delete your post so long as no-one has answered you yet.
4) No-one else can use your username
5) You can send private messages to other people and make real friends. I know that I have

Thanks reinout-g for your calcuator tips. I haven't really looked at them yet but I will.

SUP button
I really want people to learn to use the 'sup' button instead of the ^ . It makes it so much easier to read.
If you are answering a question where this is applicable could you please give a short lesson on how to use the sup button and tell them it is located just above the smilies.

Thanks everyone.

MelodyJan 30, 2014

+118725

0

theiswe:
f(x) = 3^((1/3)(x^3 - 3x)) = 0 Df = R (it says that, what does it mean?)

changed it to this:
f(x) = 3^(x^3/3 - x) -1 = 0

Answer:
x1: (0,0)
x2: (sqrt3, 0)
x3: (-sqrt3, 0)

Tried to solve this by hand. Found (0,0) alright, but cant seem to find how X can be +- square root 3..

PLEASE help fast!! ))

What you have here is 3 ^{1/3(x^3-3x)} = 0

Now 3 to the power of anything can never = 0 therefore there are no solutions.
3 to the power of anything is greater than 0.

Now Df = R is not standard maths notation. Not that i have ever seen anyway.
I think it means The domain of the function is all real numbers. (in other words, x can = any real number)
f(x) never equals zero.

MelodyJan 30, 2014

+118725

0

Duchess:
I have no idea how to use the inverse of cosine when working problems involving the Law of Cosine. I can do it on a normal calculator but when I try to type it in on this one it won't give me an answer. What am I doing wrong?? Example problem- - a=27 b=19 c=24 Solve ABC

I typed it into the web2 calc and this is what I got.
I solved for angle ABC

140130 Cosine rule.JPG

MelodyJan 30, 2014

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LDziwoki:
How do I simplify the fraction (x-6)/((x^2)-36) into reduced form?

To do this you need to recognise that a ²-b ² is a difference of 2 squares. and this is how it factorises.

a ²-b ² = (a-b)(a+b) You need to know this!

The denominator of your fraction is x ²-36 => x ²-6 ² => (x-6)(x+6)

So your fraction has become

(x-6) / [(x-6)(x+6)]

= 1 / (x+6)
The other factor cancels out.

Now instead of writing x^2 it would be better if you write x ² and I will show you how this is done.

put x then hit the sup button located above the smilies, put the 2 where it wants you to, then click out to the end and keep going with your question.
Give it a go now before you forget.

Sup stands for superscript and sub stands for subscript

MelodyJan 30, 2014

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ayshac8:
whats the answer to -2x.6

Do you mean -2x multiplied by 6?

-2x * 6
= -2 * x * 6
= -2 * 6 * x
= -12x

MelodyJan 30, 2014

+118725

0

Halper:
Is there an = sign? If so the equation would be like-
lx-6l-6=10
Isolate the lx-6l so you have
lx-6l=16
Make it 2 separate equations, one negative, one positive.
x-6=16 x-6=-16
Solve
x=24 x=-10

Halper, you have done a lot of work there and I am really glad you had a go but i think that you have misinterpreted the question.

|5−9|−6−5
= |-4| -6-5
noe, the absolute sign means how far is -4 from 0 on the number line. This is a distance, you can ignore the minus sign.
= 4-6-5
Now if you have any problems with this , draw a number line. start at 4 then go 6 in the negative direction then go another 5 in the negative direction then you'll have an answer.
You can check it on your calculator.

MelodyJan 30, 2014

+118725

0

lfc2014:
v=9r^2-r-6

This is not a question. What do you want us to do with it.
sorry I just don't know

MelodyJan 30, 2014

+118725

0

tran:
2.12765957e-7

just do it straight on your calculator

2.12765957 x shift e (-7) =
Answer: 1.94 x 10 ^-3 (to 3 significant figures)

you don't need to press the 'power of' button. If you press it you will get the wrong answer or an error message.
It is a good idea to put the -7 in brackets because otherwise the calculator might think that you mean (e ^-1) x 7

Check that you get the same answer as me.

MelodyJan 30, 2014

+118725

0

reinout-g:
erawls:
50% of 90

90 * 50/100 = 45

Thanks reinout-g
This is exactly the same but it might be easier to follow.

50% of 90
now the % means over 100 and of means x

so just do exactly what the question says

50/100 x 90 =

In computer speak we often use a * instead of a x sign.
That way it is not confusing if there are x es in the questions

MelodyJan 30, 2014