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#51 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:52:55

bobbym wrote:

2) Look at the coefficient in front of c^3 in my example. It is -27. Take the cube root of it. So n3 = -3.

Following

#52 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:45:42

bobbym wrote:

It is easier to use this:

1) Look at the coefficient in front of a^3 in my example. It is 8. Take the cube root of it. So n1 = 2. Follow so far?

yes

#53 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:42:46

bobbym wrote:

Can you extend that to a cubed form?

Well, I don't know. Let's hope that we can....

#54 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:39:22

Well, I think I could show you an example of what I was talking about. I read it somewhere :

We have :

a^2+2ab+b^2

Now we know that the first term of the root will be "a"

so...

a^2+2ab+b^2(a

"a" squared cancels the other a^2

2ab+b^2(a

Now, we know that 2ab+b^2=(2a+b)b and so if we can figure out a divisor, we will also know the root. We also know the first term of the divisor because it is always the double of the firm term of the root. (Look at the square root algorithm :http://www.basic-mathematics.com/square-root-algorithm.html)

2ab+b^2(a+b           (we find, by luck I guess, that we have "b" for the second term.)
____________
2a+b)2ab+b^2
         2ab+b^2
______________
               0

Anyway, i was searching for something like what I described.

#55 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:30:58

Ah, i was trying to find a way to find the root with only the developped form.

#56 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:23:25

Ok, byt is there a sort of long division method we could use ???

#57 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:15:54

Yes, I know, but I would still like to see how it's done ^^ By curiosity

#58 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:10:11

Nah, I don' even know what is a CAS. But I would want to do it by hand....

#59 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 03:04:12

Yes. I think that to find the square root we should use the square root algorithm for numbers.... But I'm not sure.The same goes for the cube root, maybe we should use the cube root algorithm.

#60 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 02:55:22

Ok, well if I gave you : (a+b-c)(a+b-c) or (a+b-c)(a+b-c)(a+b-c), each in developped form and I asked you what were the square root of the first and the cube root of the second, you would have : (a+b-c) and (a+b-c).

I want to extract the root in developped form!

#61 Re: Help Me ! » Finding the second and third root of a square and cube. » 2014-07-11 02:45:35

I don't have a problem exactly. Unless you want an example because you don't understand what I wrote ???

#62 Help Me ! » Finding the second and third root of a square and cube. » 2014-07-10 15:35:15

Al-Allo
Replies: 30

Hi,

Can somebody show me a ressource of how to extract the square root of a polynomial that is a square and the same goes for a polynomial that is a cube (to find its cube root)

Thank you!

#63 Re: Help Me ! » Question about limit fact. » 2014-07-09 13:35:14

Yes, I think so. He did this error 4 times in the text ^^

#64 Re: Help Me ! » Question about limit fact. » 2014-07-09 13:31:46

Ok, bu they did an error, we should read y --> -2^(-) and not y --> 2^(-)

The same thing goes for : y --> -2^(+) and not y --> 2^(+)

#65 Re: Help Me ! » Question about limit fact. » 2014-07-09 13:10:46

Hi,

I have a question about : http://imgur.com/RU7PvtJ

I actually understand what I need to do. I need to see if both one sided limits are the same to establish that the limit exists. The only thing which I just find weird is the "since y --> 2^(-) implies y<-2"

Can somebody explain me where this y --> 2^(-) is coming from ??

#66 Re: Help Me ! » Question about limit fact. » 2014-07-09 11:33:24

Maburo wrote:

Don't worry, it happens to everybody! I think you are right, I don't think assumptions are necessary for understanding - sometimes it's easier to start learning something from scratch!

Exactly!Anyway, I need to go now. Thanks (for the millionth time) for the dedication!

#67 Re: Help Me ! » Question about limit fact. » 2014-07-09 11:23:08

Maburo wrote:

Ah yes, but not all functions are continuous or defined for all x. I'm glad we got all that cleared up, though!

Yes, that's exactly the problem ! (I wasn't sure you would understand what I said.) Like you said, atleast I finally got it. I hate it when things like that happens sad In the best case, I should just forget everything that I assumed about a particular thing

#68 Re: Help Me ! » Question about limit fact. » 2014-07-09 11:16:39

Ok, thank you again for all. For some reason, my head wasn't here today... Do you want to know why I kept bugging ? I assumed, against my will, that limit and function value (the point c) were the same thing.... I don't why I did this.... Anyway...

#69 Re: Help Me ! » Question about limit fact. » 2014-07-09 11:07:36

Maburo wrote:

To find a limit for something that is not a function would probably require you to use parametric or polar coordinates. For example, you could find the limit of x as t tends to c, and the limit of y as t tends to c, for a parametric plot. Then you would have the point (x,y) for the limit as t tends to c. And for a polar plot, you would have to limit θ to avoid repetition.

In the case of your graph, there is no limit as x tends to -3 because it takes on two different values of y there.

ok, but at -9, the limit would exist, right ?

#70 Re: Help Me ! » Question about limit fact. » 2014-07-09 10:52:31

Oh, I wouldn't want to annoy you, but I have another question.

If we don't consider my graph as two separate functions(So, we don't have a function anymore, only a relation.So it doesn't pass the vertical line test), and we still want to evaluate the limit at the same point, it would still be acceptable, even if its not a function?

#71 Re: Help Me ! » Question about limit fact. » 2014-07-09 10:47:34

Ok, I understand now. My error was to think of both curves that I drew as forming one function, in the same manner as piece wise functions. But both these curves form distinct functions. Thank you!

#72 Re: Help Me ! » Question about limit fact. » 2014-07-09 10:20:03

Ok, then I understod the fact. Now, concerning my function questiom, if we take my graph, we see that at the point x=-3 we have two y's. The black and red line are both functions. But with the vertical line test, we see that this isn't a function. So, my question is, this "fact" about the inequalities doesn't necessarily need the whole (non piece wise function) to be a function.

#73 Re: Help Me ! » Question about limit fact. » 2014-07-09 10:00:06

By the way, I created a sort of graph to help myself see the verity and that's how I see it :

http://i.imgur.com/emdBFyK.jpg

Of course, there are several other types of graphs that makes the "fact" true. Would my graph be correct? ( the limit is at the discontinuous part)

#74 Re: Help Me ! » Question about limit fact. » 2014-07-09 09:48:36

Ok, but my question is, does this "sum" of function need to be a function itself ? We can have piecewise functions and non piecewise function. In other words, can we evaluate limits of non piece wise function (It doesn't satisfy the vertical line test.)

#75 Re: Help Me ! » Question about limit fact. » 2014-07-09 09:34:35

I mean, when we define a function with the use of several sub functions, we call that a piecewise function, right ?

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