13 replies to this topic

[James Noel]

Hi there, can anyone show me how to divide in algebra. I know how to do it on paper, but just wondering if I am missing out one any thing with the classpad. can it do division in algebra eg. x^3/(x^2-7X+5).
Thank you very much in advance.

[ASTRO491K]

Hi there, can anyone show me how to divide in algebra. I know how to do it on paper, but just wondering if I am missing out one any thing with the classpad. can it do division in algebra eg. x^3/(x^2-7X+5).
Thank you very much in advance.

Yes, I can tell you how to divide in algebra. It's a simple 3 step process. First go to your calculator store and then select a TI-89 and buy it. Then after turning it on, select "expand" from the algrebra menu. Finally enter x^3/(x^2-7X+5) and then press "enter" and the answer will appear on the screen.

Actually I recomment this switch from Casio to TI because I asked for some advice on which casio device to buy, in a post on this very site, and got only one reply, and it was from someone who didn't address my questions. Because there is so little known about Casio calculatores and so little interest in them, there is no point in owning one (as you have probably noticed).

[kucalc]

I'm pretty sure that on the ClassPad, using the expand command will divide those polynomials.

[James Noel]

I'm pretty sure that on the ClassPad, using the expand command will divide those polynomials.

Hi there, i have tried it over and over and nothing every happened. Do you have any ideas of what to do?

Edited by James Noel, 19 December 2009 - 05:50 PM.

[kucalc]

Wow, are you sure? Are you sure you typed it in like this: expand(x^3/(x^2-7*x+5),x)

Make sure all your x's are lowercase and you type in that comma & x at the end of the command.

[James Noel]

Wow, are you sure? Are you sure you typed it in like this: expand(x^3/(x^2-7*x+5),x)

Make sure all your x's are lowercase and you type in that comma & x at the end of the command.

I just tried it now and I got some wierd long answer.

[kucalc]

What's the weird long answer?

[James Noel]

What's the weird long answer?

I tried it again and it just spit back out the same thing x^7-7*x+5/x^2

[kucalc]

Using expand(x^3/(x^2-7*x+5),x) I think will give you partial fractions.

Try using propFrac(x^3/(x^2-7*x+5))

Type it in exactly and tell me what it says.

And if that doesn't work try rFactor(x^3/(x^2-7*x+5))

[James Noel]

Using expand(x^3/(x^2-7*x+5),x) I think will give you partial fractions.

Try using propFrac(x^3/(x^2-7*x+5))

Type it in exactly and tell me what it says.

And if that doesn't work try rFactor(x^3/(x^2-7*x+5))

Hi I just tried it and I got this anwer ~
x+44*x/(x^2-7*x+5)-35/(x^2-7*x+5)+7

[kucalc]

Yeah, that was for expand right? The expand command will give you partial fractions.

But what about propFrac and rFactor? None of those worked?

@JBB: Just tried using expand on the TI-89, same thing with ClassPad, just gives partial fractions, which is not what we're looking for.

[ASTRO491K]

Yeah, that was for expand right? The expand command will give you partial fractions.

But what about propFrac and rFactor? None of those worked?

@JBB: Just tried using expand on the TI-89, same thing with ClassPad, just gives partial fractions, which is not what we're looking for.

With the Ti-89 or Voyage 200, by entering expand(x^3/(x^2-7x+5)), the correct answer of 44x/(x^2-7x+5)-35/(x^2-7x+5)+x+7 occurs. The fractions occur because x^3 is not divisible "evenly" by x^2-7x+5. Thus the answer is x+7 plus the remainder of 44x-35 which of course can be expressed as (44x-35)/(x^2-7x+5) or 44x/(x^2-7x+5)-35/(x^2-7x+5). Again, that is because of the remainder which occurs because x^3 is not divisible evenly by x^2-7x+5. I don't know anything about the Casio cas but I suspect that the problem may be occuring because you trying expand(x^3/(x^2-7x+5),x) and possibly should be using using expand(x^3/(x^2-7x+5)) without the ,x. Again, you get the pratial fractions whether that is what you are looking for or not, because that is the correct answer. The only other possible answer that could be returned would be x+7 w/remainder: 44x-35. Signed: JBB

[kucalc]

@JBB: Yes, I know. James Noel got the the same answer as you when typing expand(x^3/(x^2-7*x+5),x) -> x+44*x/(x^2-7*x+5)-35/(x^2-7*x+5)+7

The only other possible answer that could be returned would be x+7 w/remainder: 44x-35.

Exactly. I think Noel wants wants is the ClassPad to print out the quotient and the remainder, not in partial fraction form which he thinks is the "weird answer." I'm trying to find out if there is such a command on the ClassPad that will print out x+7+((44*x-35)/(x^2-7*x+5)), just like that. Symbolix CAS, which I wrote, has a polydiv() command which will print that out. I think propFrac on the ClassPad should do it.

[supergems]

With the HP 50g:

'X^3/(X^2-7*X+5)' PROPFRAC --> 'X+7+(44*X-35)/(X^2-7*X+5)'
'X^3/(X^2-7*X+5)' PARTFRAC --> 'X+7+(-((-1276+238*\v/29)/29/(2*X-(7-\v/29)))+(1276+238*\v/29)/29/(2*X-(7+\v/29)))' ('\v/' is the square root symbol)

PROPFRAC: splits a fraction into an integer part and a fraction part.
PARTFRAC: performs partial fraction decomposition on a fraction.

supergems

Edited by supergems, 19 February 2010 - 10:40 AM.