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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What is the domain of (fg)(x)?

Your question doesn't make sense so I assume this notation is new to you.

You probably mean the domain f(g(x)) and you got it from a different question.

The domain is all the values that x is allowed to be.

(The range would be all the values that y is allowed to be.)

I hope this helps. You can ask questions like this on the back of other posts if you want to.

MelodyDec 5, 2013

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This is the graph of y=sin ^-1x
It looks like it finishes early, I don't know why, but the end points are (-1,-pi/2) and (1, pi/2)
http://gyazo.com/7f6851adf451e3505295f474e55dfd33

I am going to add more but there are mistakes in my last post so I will fix them first and I will tell you when they are fixed
It was actually the graphing on desmos that showed me my error, which is exactly what Demos is great for.

this is a graph of both on the same grid, I am short of time so I must get this post finished.

http://gyazo.com/a8e1bcc4426b67d5c773a77bd39fc6ca

MelodyDec 5, 2013

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Given that p(x)= sin^-1 x and q(x)= x+7, what is the domain of p(q(x))?

The instruction Special has given you is good but what if you didn't have access to the Demos calculator?

By the way, the Demos calculator is fabulous and I use it all the time. But mostly it should be used to check your answer or give you guidance, not to answer the question for you.

With your question you must first look at whether q(x) has put any restrictions on the domain. And no, it has not, q(x) is defined for all real x.

Now look at p(q(x))

p(q(x)) = sin-1(x+7) also written as p(q(x)) = asin(x+7)

Now, I think, AshB, that you are supposed to know what y=sin ^-1x looks like and therefore that it is restricted to -1 < x < 1

So, looking at your problem

-1 <= x+7 <= 1
-1 -7 <= x <= 1 - 7
So the domain of p(q(x)) will be -8 <= x <= -6 ( the errors that I speak about in the next post have been fixed)

I might have a play with demos and see if I can get you a graph or 2

MelodyDec 5, 2013

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Don't worry Special. We all do it sometimes. I like seeing all your posts.

MelodyDec 5, 2013

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What do you mean, is there more to this question.

MelodyDec 4, 2013

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tan (x) sin (x) + sec (x) cos2 (x)
I am assuming you mean

tan (x) sin (x) + sec (x) cos ²(x)

= sinx/cosx * sinx + 1/cosx * cos ²(x)

= sin ²x/cosx + cosx

= (sin ²x + cos ²x) / cosx

= 1 / cosx

= sec x

MelodyDec 4, 2013

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how i can use cos^-1 ?

It is the inverse of cos or arccos

You use it to find an angle.

MelodyDec 4, 2013

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A=900(1+.10/2)^2*2

what is wrong with YOUR calculator?

A=1984.5

MelodyDec 4, 2013

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x= [1/2(log13.2/log3)]

this is just a straight calculator question.

1.17430729 to 9 significant figures.

MelodyDec 4, 2013

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http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Baby_due_date

Maybe you will find this interesting.

MelodyDec 4, 2013