Simplify

RickyOswaldIOW · 2006-01-05 19:35:33

x(x-1)(x+1)
do I multiply the brackets by eachother first, or each bracket by x?

Jai Ganesh · 2006-01-05 19:48:00

Multiplication is commutative, that is 6 x 7 = 7 x 6.
When you have three terms to be multiplied, first multiply the first and the second and the result by the third.It wouldn't make a difference if you multiply the second and the third and then multiply the result by the first.
x(x-1)(x+1) = (x²-x)(x+1) = x³ + x² - x² - x = x³ - x.
(x-1)(x+1)(x) = (x² - 1)(x) = x³ - x
As you can see, the results are the same in both the cases.

When you have a(x-y), you'd have to multiply both the terms inside the bracket by a, you get ax - ay.

Rose-Red · 2006-01-05 21:53:46

or you simply can see a formula (a-b)(a+b)=a² - b² ; as a result (x-1)(x+1)=x²-1²
so x(x-1)(x+1)=x(x²-1²)=x³-x

Last edited by Rose-Red (2006-01-05 21:54:54)

RickyOswaldIOW · 2006-01-06 09:36:37

Thankyou, I was drunk
Won't happen again.

Rose-Red · 2006-01-06 09:59:01

Maybe someone could simplify this?

again, I need the whole solution, because the answer is at the end of the book

RickyOswaldIOW · 2006-01-06 10:06:12

I'd start with x/x^2, firstly I'd "reciprocal" which basically means you take the value with the power (x^2) and move it to the top, when you do this you MUST change the sign of the power:

x / x^2 = x * x^-2

I'd then do the same with the next part of the sum, giving you b - ax * x^-3. Now all that is left is

(x * x^-2) + (b - ax * x^-3), since none of the values share similar powers, I think this is as far as you can go. (Don't take my word for it, I'm new to this too).

Last edited by rickyoswaldiow (2006-01-06 10:06:35)

Rose-Red · 2006-01-06 10:23:02

well the answer is
I also tried to do that but in quite different way. Still I couldnt get the right answer. That's what I got

RickyOswaldIOW · 2006-01-06 10:41:02

Sounds like a job for Crazy Holmes

krassi_holmz · 2006-01-06 10:53:31

I think the book's answer isn't correct. We can't eliminate a.
I got the same as you.

Rose-Red · 2006-01-06 10:54:31

yeah, maybe you're right.

krassi_holmz · 2006-01-06 10:58:36

I've just read this "crazy holmes" thing.

Ha, ha, ha, that was VERY VERY... VERY
### ### ### ###
# # # # # # #
# ## # # # # # #
# # # # # # # #
### ### ### ###

krassi_holmz · 2006-01-06 11:01:22

Actually it was BAD, but I'll forgive you if you promise that you will
NEVER
NEVER
NEVER
do this again
much

RickyOswaldIOW · 2006-01-06 11:19:11

appologise, grassy homes.

Jai Ganesh · 2006-01-06 16:39:50

Very funny. First krassi_holmz becomes crazy holmes, finally, grassy homes. I really hope krassi_holmz doesn't take offence at that. Maybe, rickyoswaldiow is just being funny. But a word of caution to rickyoswaldiow. People don't like their names (or usernames) spelt or pronouned wrongly.

krassi_holmz · 2006-01-06 22:35:27

Yes, wildrocky, yes.

RickyOswaldIOW · 2006-01-07 04:31:12

No offence intended. I play online FPS games and my language in that would get me banned in a flash here. You **...

mathsyperson · 2006-01-07 04:56:01

I'm a bit late here, but I agree with everyone else.

I'd just scale up the left fraction by x to get a common denominator of x³, and then they can easily be added together.

krassi_holmz · 2006-01-07 05:41:20

Yes, but the "a" cannot be removed.

Math Is Fun Forum

#1 2006-01-05 19:35:33

Simplify

#2 2006-01-05 19:48:00

Re: Simplify

#3 2006-01-05 21:53:46

Re: Simplify

#4 2006-01-06 09:36:37

Re: Simplify

#5 2006-01-06 09:59:01

Re: Simplify

#6 2006-01-06 10:06:12

Re: Simplify

#7 2006-01-06 10:23:02

Re: Simplify

#8 2006-01-06 10:41:02

Re: Simplify

#9 2006-01-06 10:53:31

Re: Simplify

#10 2006-01-06 10:54:31

Re: Simplify

#11 2006-01-06 10:58:36

Re: Simplify

#12 2006-01-06 11:01:22

Re: Simplify

#13 2006-01-06 11:19:11

Re: Simplify

#14 2006-01-06 16:39:50

Re: Simplify

#15 2006-01-06 22:35:27

Re: Simplify

#16 2006-01-07 04:31:12

Re: Simplify

#17 2006-01-07 04:56:01

Re: Simplify

#18 2006-01-07 05:41:20

Re: Simplify

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