OMG! Finally able to post! Function Question -

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OMG! Finally able to post! Function Question -

Postby Borrowedhalo on Wed Nov 14, 2012 6:23 pm

Oh my, what a morning!

I was about to start to cry. It's like this math is a "secret".

So, a little background...I'm a mom trying to help her dyslexic and very shy son figure out how to do some of his Algebra II homework.

I can't show you what I've tried, because I haven't tried anything. The problems look like this: y = [[2x]] or y = 2 [[x]].

It's a function to graph. I know how to graph functions, but I don't know what that double bracket thing means. In the book it has the problems and then it says "Page so and so"...I looked on that page and NOTHING tells me what this double bracket thing means.

So, please tell me what to do here. If you don't want to "give me the answer", fine. Just walk me through a similar problem. I just need clear steps to walk my son through it.

Thanks.

Kristine
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Postby maggiemagnet on Wed Nov 14, 2012 9:32 pm

Unfortunately, that notation can be used for at least two different functions. If your book doesn't say which one it means, then there's no way to advise. Sorry! :shock:
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Ok, same question; second try

Postby Borrowedhalo on Sun Nov 25, 2012 12:43 am

Hi purple mathers!

Ok, so if you've read my posts before, you know I'm a mom trying to help an LD son learn Algebra II. Personally, I never had to take it, so I have never seen some of this stuff before.

When I asked this question last time, a poster said she really couldn't help because there are at least 2 different things that this notation could mean. I didn't have the book with me at the time, so we were stuck.

Thankfully, the teacher is going to let him make up this and some other sheets that he just didn't get......so, alas, here it is.

The questions are like this: Graph each function - 1.) y = [[x+2]]

I didn't know what the double bracket thing meant. Now I have the book. So.......

It says, "The greatest integer, written f(x) = [[x]], is one kind of step function. The symbol [[x]] means the greatest integer less than or equal to x. For example, [[3.25]] = 3 and [[-4.6]] = -5."
Then it shows this picture with a bunch of lines with solid dots on one side and open dots on the other side.

So...yeah. Someone dumb it down for me ;p! I don't know how to apply the information to solve the problem.

Thanks.

Kristine
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Re: OMG! Finally able to post! Function Question -

Postby maggiemagnet on Sun Nov 25, 2012 3:05 am

I was going to give you a link, but most ofthe links seem to be videos, which you can sort through yourself. This page might be helpful.In your case, because you're an adult (and a parent), you have real-world experience that you can apply. This is the function that rounds DOWN to the nearest integer (whole number or its negative). You could maybe think of this as the rule that pays you for piecework. If you run out of time halfway through making a "piece", they only pay you for the pieces you finished, which is the whole number just before your actual amount. If you "finished" ten and a half pieces, they'd only pay you for ten.
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